Last update: November 12, 2022

How to Cycle Your New Aquarium? The EASY Way (Beginner Friendly!)

You bought your new aquarium, filled it with water. The next step is adding fish, right?

Hold up!

If you add your fish now, they will soon be dead.


Before you add any fish to your aquarium, there is one important thing you must do:

Cycle it!

To beginners, the nitrogen cycle is considered the most confusing part about owning an aquarium.

But don’t worry – it doesn’t have to be this way.

I am going to show you how to cycle your aquarium the right way, with fishless cycling – it’s much easier than it looks.

What is the nitrogen cycle and why is it so important?

You may have heard the terms biological cycle, nitrification process or break-in cycle. Don’t get confused, these all refer to the same thing I cover in this guide – the nitrogen cycle.

Before I show you how to perform a cycle, it’s important that you know what is going on behind the scenes.

Imagine swimming in a pool surrounded by your own pee and poop.

Sounds horrible, right?

Your fish feel the same.

Unfortunately, there is no such thing as a toilet for fish. So, your fish will poop and pee in the same water they swim in. That’s like you pooping in your bedroom!

Bad smelling fish poop in aquarium next to goldfish

As your fish’s pee, poop and other waste breaks down, it releases ammonia into the water. Ammonia is a toxic substance that will kill your fish. Death by poop? No thank you!

Luckily, nature is on your side. The nitrogen cycle prevents your fish from meeting this horrible end.

In this natural three-stage process, you encourage beneficial bacteria (good bacteria) to become established in your tank and filter, keeping your fish safe from ammonia.

Let’s take a closer look at the nitrogen cycle…

The nitrogen cycle process

Waste breaking down into ammonia, nitrite and nitrate in aquarium diagram

See this diagram? This is the nitrogen cycle in a nutshell. Let’s break it down.

Stage 1: Ammonia (Harmful)

Poop waste breaking down into ammonia diagram

It begins with waste. Poop, pee, uneaten fish food and rotting plants all give off ammonia as they break down.

Ammonia will continue to build up in your tank, reaching deadly levels. That is, until a beneficial bacteria that eats it begins to form. These bacteria naturally appear in your tank on their own and once they grow in number, they can eat ammonia as quickly as it appears.

You know these bacteria are present in your aquarium when your ammonia levels begin to decline, typically after the first week. And when that happens, you know that you are entering the second stage of the nitrogen cycle…

Stage 2: Nitrites (Harmful)

Ammonia converted to nitrite by bacteria diagram

As your ammonia levels begin to decline, you notice that the nitrite levels begin to rise. This is because the bacteria that eat the ammonia give off a new chemical – nitrite.[1]

Just like ammonia, nitrites are highly toxic to your fish.

But not to worry because as your nitrite levels rise, a second bacteria appears in your aquarium. It’s favorite food? Nitrites

Once this good bacteria grows in number, it can eat nitrites as quickly as they are produced.

You know this bacteria is present in your aquarium when you see your nitrite levels begin to fall. When this happens, you have entered the final stage of the nitrogen cycle.

Stage 3: Nitrates (Harmless)

Nitrite converted to nitrate with bacteria in aquarium diagram

As your nitrite levels decline, you notice that the nitrate levels rise. This is because the bacteria that eat nitrites give off a new chemical – nitrate.[2]

Nitrates are the final product of the nitrogen cycle. And, they are relatively harmless to your aquarium, at least in small amounts.

But as nitrates build up, they can become toxic to your fish. Fortunately, nitrates can be lowered back to harmless levels by performing a water change. In fact, this is one of the reasons why you should be performing regular water changes on your aquarium.

Important: With just a single letter separating nitrites and nitrates, it’s easy to confuse the two. Remember… Nitrites are highly toxic to your fish while nitrates are not harmful in small amounts.

And, that’s really all there is to the nitrogen cycle!

That wasn’t so hard, was it?

When you cycle your aquarium, you are simply forcing your tank to undergo the nitrogen cycle.

The reason you need to cycle your aquarium is so that these two beneficial bacteria can grow to the point that they can eat the harmful ammonia and nitrites as quickly as they produced.

FishLab Fact: The bacteria that convert ammonia to nitrites and nitrites to nitrates are called nitrifying bacteria.

At this point, you can consider your aquarium effectively cycled.

It’s important to understand that the nitrogen cycle is continuous. While you can’t see it, this cycle is constantly happening in your aquarium, keeping your fish safe from harm.

What happens if you don’t cycle your aquarium?

The nitrogen cycle is a funny thing in that it’s going to happen whether you want it to or not.

If you add your fish to an uncycled aquarium, the food and poop breaking down is going to introduce ammonia, which kick-starts the cycling process.

In fact, this is the very idea behind fish-in cycling – a method of cycling an aquarium that is best left to the experts.

Just one problem…

You see, your fish are in the tank while toxic ammonia and nitrite levels rise. To say these things are dangerous to your fish is an understatement.

This toxic environment is incredibly harsh on your fish – most fish cannot survive this cycle, and the ones that do are more susceptible to disease and don’t live as long.

So while a tank may cycle itself without any effort on your part, there is no guarantee that your brand new fish will survive it.

Unfortunately, if you have already bought fish to go with your new tank, a fish-in cycle maybe your only option.

If you are in this unfortunate position, don’t panic. I created a fish-in cycling guide that will give your fish the best chance of survival.

How long does it take to cycle your aquarium?

The other day I was stocking up on supplies at a major pet store. In the next aisle, I overheard a conversation between an employee and shopper who wanted to buy a pet fish.

I won’t bore you with the details, but the employee was working hard to pitch this shopper a new tank – claiming that modern tanks only take one day to cycle. After this 24-hour period, it’s safe for fish.

Those of you with a bit of experience will see right through this lie.

But for those of you who are new to the hobby, cycling your aquarium is going to take a lot longer than that!

How long?

Depending on who you ask, cycling your aquarium can take anywhere from 2 weeks to 2 months.

The best answer:

It will be finished when it’s finished.

If you are lucky, your cycle might be short. But don’t be upset if it takes longer – we’ve all been there before and it sucks!

The problem is that the bacteria you introduce in the cycle grow very slowly. And all you can do is wait.

It is for this reason that you should cycle your aquarium before you buy your fish. Don’t add them to your aquarium before it has cycled.

Remember… Cycling isn’t an instant process. But you have to do it if you are planning on keeping happy and healthy fish.

But don’t stress – I’ll cover some tricks that you can use to speed up the cycling timeline later in this guide.

If you do not have the patience to cycle your aquarium, then fish are not the right pet for you.

How to cycle your aquarium the easy way

There are two ways to cycle your aquarium:

Fishless cycle – A beginner-friendly and harmless method to cycle your aquarium

Fish-in cycling – Recommended only for experts because this method could potentially kill your fish

As you probably guessed, this guide covers cycling a tank without risking the lives of fish. And, it is the most popular and common technique used to cycle aquariums.

Note: There are many ways to perform a fishless cycle. This beginner-friendly method, if followed step-by-step, is almost foolproof.

What do you need to perform a fishless cycle?

When it comes to cycling your aquarium, you only need three products…

1. An aquarium test kit

API Freshwater Master Test Kit for aquariums

The nitrogen cycle is an invisible process. The only way to truly understand what is happening inside your tank is to test for it. And, the most popular way to do that is with an aquarium test kit.

I recommend buying a master test kit like the one above because it contains every test that you need to cycle your aquarium at one low cost.

Learn how a test kit works. Check out FishLab’s aquarium test kit guide.

2. Ammonia

Fritz Ammonium Chloride for fish tank cycling

Instead of waiting for waste to break down into ammonia, add it directly. This will make it easier to keep ammonia levels constant.

Important: Use 100% pure ammonia. Many household ammonias contain scents and additives, and this is going to kill your cycle before you even start. Stick to pure ammonia, like the one above.

3. Dechlorinator

API tap water conditioner to dechlorinate water

Are you using tap water to fill your aquarium? Be aware that it contains chloramine and chlorine, two chemicals that kill beneficial bacteria in your tank.

Fear not! Adding a good water conditioner to your aquarium will dechlorinate your water, making it safe for the beneficial bacteria (and fish when you finally add them).

Use this whenever you add tap water to your aquarium.

Have these on hand? Good. You are now going to learn how to cycle your aquarium in 6 simple steps.

FishLab’s 6-step cycle method

Cycling your aquarium is easy…

As long as you carefully follow the instructions!

So, slow down and make sure you understand each step before moving to the next. If you don’t, you risk ruining the cycle. And if that happens, you will have to start over.

Step 1. Set up your aquarium

You know all that equipment you got with your aquarium? Well, you need to set all that up.

Heater, filter, air pump, substrate, plants… Get it in there.

Why do you need your tank fully set up?

Well, beneficial bacteria needs a surface to cling to, namely your substrate and filter media. In fact, most of the bacteria will call your filter home.

Once your tank is set up, you want to keep any electrical equipment, such as heaters, bubblers and filters, switched on throughout the cycling process. Doing so encourages the beneficial bacteria to grow and may even make your tank cycle faster.

Note: Beneficial bacterial prefer temperature between 65-85 degrees Fahrenheit. Growth is slower outside of this temperature range – which can cause your cycle to take longer to complete. Check your water temperature with an accurate aquarium thermometer.

Step 1 Summary

  • Set up your aquarium
  • Turn on all electrical equipment

Step 2: Check your pH

This is perhaps one of the most commonly missed steps when it comes to cycling your tank – and a common cause of failed cycles.

You see, the cycling process can slow down or even stop if the pH level of your water drops below 7.

Since the master test kit includes a pH test, it would be silly not to use it now.

So, check the water you added to your aquarium with your test kit. If it’s below 7, you need to raise your pH before moving to the next step.

Good news! This won’t be a problem for most of you because the majority of water supplies across the United States test at a pH that is greater than 7.

Even so, you want to continue performing pH tests throughout the cycling process. You see, the beneficial bacteria in your tank give off acids that lower the water pH over time.

If you notice that your pH levels drop under 7, a simple 20% water change is all that’s needed to raise the pH and get the cycle going again.

So, make sure you test your pH regularly and adjust it if needed.

Step 2 Summary

  • Test the pH of your water
  • Adjust when lower than 7 pH

Step 3: Add your ammonia

In a brand new tank, there won’t be any waste, meaning nothing to break down into ammonia. So, we must add it ourselves.

Simply take your Fritz Ammonia and read the instructions.

At the time of writing this, one level teaspoon of Fritz Ammonia per 100 gallons of water will give you an ammonia level of 4 parts per million (ppm).

You need to know how much water is in your aquarium in order to add the correct amount of ammonia. Use FishLab’s gallon calculator if you are unsure of just how much water your tank holds.

So, measure out your ammonia…

Fish tanks less than 40 gallons: Aim for 2 ppm

Fish tanks more than 40 gallons: Aim for 4 ppm

While you can steal the measuring spoons from your kitchen, I recommend having a dedicated set of measuring tools for your aquarium.

You now want to make sure that you have added the correct amount of ammonia. And to do this you are going to use your aquarium test kit, which will give you a result in ppm

But before you do that, you want to let the ammonia sit for an hour, so that it evenly distributes throughout the water. Next, measure the ammonia levels using the ammonia test from your master test kit – Make sure you follow the instructions provided by the test kit for accurate results.

If your ammonia readings are less than the above levels, add more ammonia and re-test.

If your ammonia levels are higher, perform a water change. Doing so will swap out your high-ammonia water with ammonia-free water, lowering the levels.

Record the amount of ammonia that you added. You will need that information in the rest of the steps.

Ammonia levels higher than 5 ppm can actually slow down the cycling process.

Now, the next part will test your patience. Check your ammonia levels each day with the test kit. This is as much as you can do for now. You are waiting for your ammonia levels to drop.

This typically takes a week. Once a week has passed, it’s time to move onto the next step.

Bookmark this page so that you can easily find it when you are ready for the next step!

See you next week!

Step 3 Summary

  • Add ammonia to your aquarium
  • Daily testing to monitor ammonia levels
  • Don’t forget to test the pH every few days

Step 4: The ammonia eating bacteria appears

After a week has passed, it’s time to test for nitrites. So, grab your nitrite test kit and check the levels.

If your test comes back positive, congratulations – your cycle has officially started!

Now, it’s important to remember that this bacteria feeds on ammonia. And the only thing adding ammonia to this aquarium is you. If your ammonia levels reach zero, this bacteria will starve, and you will have to start your cycle all over again.

So, we are going to give this bacteria a little more food. Add half the amount of ammonia that you added on day one, but make sure that your ammonia levels remain under 5 ppm.

Now what you want to do is monitor your nitrites, testing daily. You should notice the nitrite levels continue to rise. Once you see your nitrite levels start to drop, it’s time to move onto the next step.

See you again in a few days!

Step 4 Summary

  • Once nitrites are detected, add a half dose of ammonia
  • Ensure ammonia levels are less than 5 ppm (but greater than 0 ppm)
  • Daily testing of ammonia and nitrite levels
  • Don’t forget to test the pH every few days

Step 5: The nitrite eating bacteria appears

To confirm that the nitrite drop is due to the beneficial bacteria, use your test kit to check for nitrates. If they are present, you are now in the final stage of cycling your tank.

Now, we still want to make sure that the bacteria has enough food to eat. So add a half dose of ammonia as needed, each day if you have too, to keep the levels above 1 ppm.

Continue testing. When you can add a half dose of ammonia and both your ammonia and nitrite levels read zero 24 hours later, your nitrogen cycle is complete.

Woo! Home stretch… Just one more step to make it official!

Step 5 Summary

  • Test to confirm nitrates
  • Daily testing of ammonia and nitrite levels
  • Add half doses of ammonia every few days
  • When both ammonia and nitrites show <0.2 ppm, swap to daily dosing
  • Test until both ammonia and nitrites read zero 24 hours after dosing
  • Don’t forget to test the pH every few days

Step 6: The Final Test

You are so close. You just want to make sure that your tank is fully cycled. To do that, one last test is in order…

Once your ammonia and nitrite levels reach zero, add a full dose of Fritz Ammonia, the same amount that you added on day one. Now, will need to wait one last time…

Check back in 24 hours. Test your ammonia and nitrite levels. If both read zero….


Your patience has paid off, and your tank is now fully cycled.

If you record your test kit readings each day, you will have a clear understanding of the nitrogen cycle.

This chart is from the last time I cycled my tank:

Cycling an aquarium chart

It took me 28 days to cycle the aquarium.

You see a distinct rise and fall of ammonia and nitrites as the beneficial bacteria become established in the tank. You can also see how nitrates drop at each water change.

I highly recommend recording the results of your test kits each day. Not only will it give you a better understanding of what is happening in your tank, but you can also use the results for troubleshooting.

Now that your tank is cycled, the bacteria colonies are large enough to remove ammonia and nitrites as quickly as they are produced…This nasty stuff won’t be harming your fish anytime soon!

But before you add your fish, you want to perform a water change to remove those built up nitrates.

Speaking of which… You should add your fish to your tank now. If you don’t plan on adding fish just yet, keep dosing the tank with ammonia daily. This will ensure that the beneficial bacteria don’t starve. If the bacteria starve and dye, you are going to have to cycle your fish-tank all over again.

It might have felt like a lot of effort, but your hard work will be rewarded once you see just how healthy and happy your fish are. And, it’s all thanks to your newly cycled tank!


Phew, you did it! You should be proud of yourself. Your patience has paid off, and your tank is now cycled.

By cycling your aquarium, you give your fish the best possible chance to live a happy and healthy life.

Just remember that once started, the nitrogen cycle consistently runs in the background of your aquarium.

But you are not home free just yet.

You still need to continuously monitor your ammonia and nitrite levels to ensure that something hasn’t gone wrong. I recommend that you include testing your tank as part of your maintenance routine.

How did you cycle your aquarium? Let me know in the comments below!

Ian Sterling

Ian Sterling, founder of, began his aquarium journey over 30 years ago, driven by a deep fascination for fish and their diverse personalities. His website,, is dedicated to making fishkeeping accessible and enjoyable, offering beginner-friendly guidance, expert insights, and a community for aquarists to connect and share experiences.

Comments (752)

Fantastic explanation of what is going on with the cycle.

I do have a question about the cycle and a problem that I cannot seem to clear. I have a 20 gallon tank with a single crayfish in it. Decorated with some rocks for hiding and fake plants since he kept eating the real ones (in a previous tank). I used to feed him Omega One Veggie Rounds but changed to Omega One Shrimp and Lobster pellets because they are tiny and I never see leftover food.

The problem is that I cannot seem to get the ammonia levels down. I am performing weekly 25% to 40% water changes. Yet a *day after* the water change, the ammonia is still coming in at 2.0 ppm. I regularly see it spike to 4.0 by the end of the week. I *always* add conditioner when I perform water changes.

My nitrite and nitrate levels *always* come in at 0. And my water naturally has a high pH at 7.8. (I have tried adding reducer but it does not seem to do much.)

I do not think it is my maintenance habits or schedule since I also have a 40 gallon tank with cichlids, snails, and catfish and everything is fine there.

It seems as if my BB does not exist yet after a 3 plus months I am not sure how this is possible. (And the tank went though a cycle before I added the craffish.) Is there a way to test for this with the crayfish in the tank? Do I need to start a new tank? Is there anything I can add (plants, chems, whatever) to kick start this process again?

Any advice would be greatly appreciated. Thanks.

Hi Jason,

That does sound strange indeed.

The most troubling part is that after 3 months you should eventually notice nitrites and nitrates start to appear as beneficial bacteria gets established in your aquarium, even if you skipped cycling your tank prior to adding your cray – this is the basic concept behind fish-in cycling.

The problem seems to be that beneficial bacteria is not present in your aquarium, otherwise your nitrate levels would not be zero.

Based on the information provided, and this is a stab in the dark, I have to wonder if there is enough surfaces in your tank for beneficial bacteria to cling to, namely in your filter. Perhaps load it up with a good biological filter media like ceramic rings? This will give a place for your bacteria to establish and grow.

Otherwise something else is preventing beneficial bacteria from becoming established in your tank.

Thank you for the fast response. I am using a Aqueon QuietFlow (size 20 I think). Not sure where the rings would fit in there. Should I look at a different filter that could accommodate the additional media? I have seen posting and videos about DIYing the quietflow to add additional media or even replace the carbon based filter with pads and rings.

Interesting, I know many people who have successfully ran Aqueon Quietflows with out any issue. I’m, sure you are all over it, but you are not rinsing the filter media in tap water by chance, are you?

When it comes to HOB filters, a pre-filter sponge is probably the easiest way to add extra media for beneficial bacteria to cling to. However, if your cray is particularly pinchy, he may rip it apart.

Before you go down that route, I would record everything you are doing over the course of your week, take a photo of your set up and post it one of these online forums, it’s very likely that someone else has experienced the same problem as you and will be able to identify a quick solution!

No. Definitely not rinsing the filter in tap water. I am scoping water from the tank *before* I do a water change.

Appreciate the feedback. Will post to one of the forums. Thank you.

So to hide my time with all the craziness going on in the world I am currently working on cycling a 20 gallon and a 5 gallon. I unfortunately can’t find the ammonia as of right now so have been using fish food instead XD. Anyway any tips on using fish food instead of the pure stuff?

I am currently at 7.4 pH and about 2ppm of ammonia in the 20 gallon(it could be 3ppm as it was slightly darker than the 2ppm mark but lighter than the 4ppm). I am currently on day 5 of my cycle attempt… This is the first day I have been able to test properly because I didn’t realize you had to add drops from both bottles. Whoops. It’s got three rooted plants(Amazon sword and a stem plant whose name I have forgotten) and a few marimo balls. They seem to be growing super well(the sword has sprouted 3 new leaves since I got it); that’s a good sign right?

The five gallon is currently waiting on an appropriately sized filter before I start testing that.

Thanks so much for the guide, it’s lovely and clear and explains things well. This is the first one that actually helped me understand why cycling was needed. A lot don’t explain it as well and so it just seems like they are going “just do it because we told you to”. Anywho, I have had fish in the past but thanks to ignorance they haven’t lasted too long. I am super excited to get this going right and properly this time round.

This is a great article and I bookmarked the page.

I will be starting the cycling process this weekend.

I do have one question, though.

Would it help to add one of those “beneficial bacteria” agents?

Someone recommended either stability by Seachem or Tetra Safe Start.

Hi Sharon,

Thanks for the lovely feedback.

Regarding “instant starter products” they can indeed speed up the cycle. The biggest concern with them is that these products contain living bacteria inside them. This means that improper storage or exposure to cold and heat can kill them – you might buy a bottle of dead bacteria. Delicate little things. Also, make sure you check the expiry date on the packaging!

Then there is the fact that different brands use different strains of beneficial bacteria. Many argue that only the strain found in Tetra Safe Start or Dr Tims is the same as the bacteria that establish in your filter. Others disagree.

The reason I didn’t include instant starter products in this guide is that your aquarium will eventually cycle regardless, and there is no guarantee that these products will speed your cycle up.

While many people preach the wonders of these instant cycle products, others claim that they didn’t help their cycle time at all. YMMMV but there is no harm in trying.

If you do go down this route, be wary of the instructions on many of these instant cycle products. Despite claims, I would be particularly mindful of adding fish immediately to a brand new tank.

Good luck this weekend. Would love to hear your experience with cycling your aquarium.

Ok, thanks!

I will be careful, and I don’t plan on adding a betta until I am sure that the process is completed.

I am more interested in doing this the right way than the quick way!

Mr. Sterling,

My aquarium is not showing any signs of nitrite, but the ammonia levels are falling. I am using the API master test kit to test daily.

This is the 9th day since I set up the aquarium (2.7 gallons), and started by following the instructions on this page.

Today, the ammonia level was 1.0 ppm, the nitrite was 0, the ph was 7.6, and the high ph test showed 7.4. The only thing that I have added is Prime, which I read about on the water conditioner page.

Any suggestions?



Hi Sharon,

That does sound puzzling, ammonia doesn’t just disappear, it has to go somewhere.

Firstly, have you checked to see if your nitrite test kit is within the expiry date?

Next, I would test for nitrAtes, it’s possible that you are further down the cycle than you think.

Can I also ask, what are you using for your ammonia source?

I tested all three…ammonia is still 1.0 ppm. The nitrite is at 0, and so is the nitrate. I bought both of the products that you recommended…the API freshwater kit (exp date is 2023) and the Fritz Pro Aquatics ammonium chloride.

I used Seachem Prime as my conditioner.

Should I try adding more ammonia to get it back up to 4.0 and start again?

I did have to add some water to the aquarium due to evaporation.



Everything sounds in order on the product front.

Because your tank is only 2.7 gallons, I would suggest using a half dose (raise it to 2ppm) I would then take daily tests to see if it drops again.

Seachem prime is fine to use during aquarium cycling. While it does “neutralize” ammonia and nitrites, they can still be eaten by beneficial bacteria.

I just had a thought, does your tank have a filter? This is where beneficial bacteria hang out. While a small amount will live in your tank, most of it will live in your filter media. I have been giving you advice based on the assumption that you have a filter (fine sponge or ceramic rings work great as a home for beneficial bacteria)

It would be hugely beneficial if you write down your:

setup (equipment, such as heater, filter, lights etc.)
Water parameters (ph, temperature,
Your routine (the nitty gritty – do you add prime after adding water to your tank or before, etc.)

This way I can check out your routine and see if there is somewhere that you are going wrong. It’s hard to get the full story out of a few back and forth sentences.

I understand this is all very frustrating, but I’ll be here until you get it done properly, so we can get your tank setup for a happy and healthy betta.

I have the Penn-Plax Vertex Desk Top aquarium kit with a Cascade 20 power filter. It has poly fiber carbon cartridges. I am only using one cartridge in the filter right now, but it looked like there was room for two if necessary. I have a Tetra submersible heater for 2 to 15 gallons 50 watt heater. The temperature usually ranges from 77 to 80 degrees. I used gravel for the bottom. I don’t have lights set up yet. I was waiting for the cycling process to finish. I read that bettas don’t care for bright light, so I am going to use a low level led light.

The ph levels have been a constant 7.6 every time I test the water. When I first set up the tank, I used a combination of betta water that I bought from Wal-Mart and spring bottled water. Our tap water is rather bad. I lost my first betta due to bad water (even though it had been sitting out for 3 days and had Tetra Betta Safe conditioner), and I don’t want to do that again!

I used Tetra Betta safe for a water conditioner when I first set it up, and I use Prime when I have to add water due to evaporation (maybe every 4 or 5 days). I usually check the water every two days for ammonia, and have started checking for nitrites, and ph at the same time.

I will do as you suggest and bring the ammonia level up to 2 ppm, and check it daily.

Any other advice would be greatly appreciated!


Thanks for the comprehensive reply Sharon.

I am not too familiar with the Cascade 20 Power Filter, do the instructions state to add both cartridges? . If you find the cartridge gunking up too quick, grab a fluval pre-filter sponge, it will catch the bigger debris, filtering it out before it reaches the cartridge inside the HOB filter.

All your parameters look pretty normal and shouldn’t impact the cycling process at all. I do not have any experience with using spring water, but I am doubtful that would cause a cycle to slow or halt – not unless there was something funky in it.

After you bring the ammonia back up to 2 ppm I’d give it another 3-5 days and monitor what happens to the ammonia. Unless you have somehow re-started your cycle, this should begin to decrease at this point in time. When you do go to top the water up, make sure you test the ammonia and nitrites before and after, just to see if anything fishy is going on here.

Unfortunately, much of cycling an aquarium involves patience and waiting for time to pass.

Please update me as to your findings.

You don’t talk about PH LEVELS. Both of mine are off the charts.High would be an understatement.I do water changes and test once a week. So what am I not doing right?

Thanks for the article. I’ve had some natual pond /fish experience… But I didn’t realize aquariums were so fragile. Ignorance of this system I think this explains the guppy die off we are experiencing. It’s been about 2 weeks since I introduced fish and we have lost about 5 guppies. *I will pick up a test kit tomorrow! Some pond water (plants) has been introduced, so I’m hoping the transferred beneficial bacteria will speed up the cycle. One female looks pregnant remains… So hopefully the cycle will balance and her fry will be born into a healthy system.

Hi Peter,

Unfortunately it’s a part of the hobby that many beginners are unaware of. Excellent idea on the test kit, it’s basically the only way to determine the health of your aquarium. I hope your remaining guppy pulls through – fish-in cycling is tough and many fish don’t make it.

Hi Mr. Sterling I have been trying to do a fishless cycle for about a week and three days. I used Dr. Tims ammonia for cycling and dosed up to 4ppm which was a bit high for a 5.5 gallon but I didn’t see it necessary to do a water change to bring levels down. My ph has stayed constant at 7.4-7.6. For a week and three days my ammonia has stayed constant at 4ppm. When should I start to see a drop? I have been keeping my aquarium light off, my filter running, my heater on (77F), and used tap water conditioner. I have also noticed this white slimy substance on my heater cord. I’m wondering if it’s some sort of algae or fungi. I haven’t touched it yet.

Hi Ben,

Hi Ben, a normal cycle can take up to 3 months, so you are not at a point to start worrying yet. I assume you have filter media inside your filter for the beneficial bacteria to live in?

If I was in your position, I would perform a water change, to help reduce your ammonia down to 2 ppm. You could then add bacteria supplement like DR tims or Tetra Safe start. Whether these bacterial supplements help is up for debate, but there is no harm in trying. Some people swear by them while others find their is no improvement ion cycling speed.

As for the algae, that could be biofilm, which is considered harmless.

Im familiar with cycling tanks but circumstance makes me wonder. Here in central Kansas we have in general poor water from the tap. Im cycling a 40 gal breeder. Chloramine is present . Off the tap ammonia=.35 , nitrite=.20 , nitrate=.30 , PH=8.1 and on strip test watershows hard. I used 2 bottles of Tetra Smartstart ( bacteria) , Dechlorinated with Jungle Start Right for slime coat and Seachem Prime to deal with neutralizing the ammonia. In addition I put in cycled filter media in HOB filter , added a homemade sponge filter and tossed in a handful of Hornwort. Then added the 2 female swordtails. Day three the ammonia is testing .50 while everything else remains the same. In this situation I feel the regular water changes will do more harm than good. Aged 5 gallon jugs show no change in water peramiters. So I intend to top off water and moniter closely . Can you use the Prime to keep Ammonia in check until its done cycling without massive water changes ? The ammonia keeps climbing in the tap . It had been around .20 for several months prior.

Hi Ty,

You can use prime to keep ammonia in check during a cycle. It “binds” the ammonia – it’s still there for beneficial bacteria to eat, it’s just rendered harmless to your fish.

Marineland® Total Care Aquarium Bacteria
Does this work for a new tank cycle?
How many Oz. needed for a 60 Gallon?

Nitrites won’t go down, what’s the fix?

Hi William,

If nitrites won’t go down then your tank isn’t cycled – a water change can help to quickly reduce nitrates. You can also render nitrites harmless using a water conditioner like seachem prime.

Bacteria additives can help cycle a tank quicker, but it’s not guaranteed. As for dosage, it should be clearly written on the label.

Dear Ian,

Congrats for your guide! Really detailed and comprehensible.

I have a small 5 gallon aquarium.
I intend to put in some chili rasboras and two little shrimp.
My cycling is on the last stage:

4ppm of ammonia are consumed completely in 24 hours by the bacteria.

The nitrites though need more time than 24 hours to drop to 0. They need around two days.

Probably the population of my second group of bacteria is not so big yet.

Nitrates are around 10-20.

My dilemma is the next:

I will leave in two days for about 8-9 days.
The cycling process is probably near the end.

1) If I won’t put any fish, the bacteria will probably starve and my patience will be lost in vain.

2) If I make a water change and put some fish in, they will produce some ammonia in order to maintain the ongoing cycling process, but there is the danger of them dying because of the relatively slow rate of nitrites consumption by the bacteria.

(A friend will feed the fish in the second case, but I cannot ask him to do all the testings and ammonia adding of the first case as he has no experience)

Do you think I can add some chilli rasboras and two little shrimp or they have a big chance to die? What would you do in my position?
Thank you very much in advance!


Hi Michael,

Thanks for the lovely feedback.

Ugh, how frustrating, you are so close to the end.

You know, it’s perfectly possible that in two days, your tank will be completely cycled.

Even so, I’d be hesitant adding fish and risking them being overfed by your friend (carers love to overfeed) or in case something else goes wrong.

Why not instead of having him feed the fish, he adds pre-measured amounts of ammonia each day? Buy 9 small containers, fill them each with a measured amount of ammonia and he can add one at a time. It’s fool proof.

This way you will return to a completely cycled chance and there is no possibility of dead fish.

Hello Ian,

Thank you for your quick reply!
Your advice is really good and this way I can avoid having any dead fish and especially (if this happens) having them decaying in the tank producing even more ammonia harming the surviving ones.

It would be good to be present during the period I add the fish in order to encounter quickly any possible complications.
I will follow your advice and keep you updated!
Thank you very much!

Hi again Michael,

It sounds like a good plan – returning home to dead fish would be awful.

I hope you have a safe trip!

Hello Mr. Sterling, lately I noticed my tank drop to a ph level of 6.0 during my fishless cycle. I did a 20% water change and tested the next day and it was about 6.6. I didn’t touch it and the next day it was at 6 again. I don’t know how it dropped so quick but I did a 40% water change and today it’s testing 6.8. How can I get the level to be over 7? My tap water ph is 7.6 and all I have in my aquarium is gravel and a fake plant. Also the water changes lowered my ammonia so should I redose?

Hi Kyle,

You should test the KH (Also referred to as alkalinity) of your water. KH is a buffer that helps water resist pH swings. It’s possibly that the KH of your water is low.

Also, a water change will indeed lower ammonia, simply dose it back up to your desired level.

I don’t have a good kh water tester but my multi purpose test strips read 0. Is there any permanent solution to bringing my kh levels up. And if so how would I bring my ph up as well. Water changes aren’t working so good for me. Thanks, -Kyle

I’d recommend using an aquarium test kit, like this one Not only will it be cheaper in the long run, but they are also more accurate. Only downside is KH is sold separately.

You could also double check your water at your local fish store. Many offer water testing.

Baking soda is the easiest way to raise pH – 1 teaspoon per 5 gallons is considered safe for small increases. You can mix this prior to adding water to your tank during water changes. Test and add more if needed once it has completely dissolved.

Otherwise crushed coral can be added to the substrate to readily increase pH.

Mr. Sterling,

I am now in the 2nd month of cycling. You were so right when you said that you have to be very patient!

I am adding ammonia as needed as you advised in your guide. I do have readings of nitrites and nitrates.

I have tested every day, and the nitrites have risen, but so have the nitrates. The nitrites are not falling yet, but I am concerned about the high rate of nitrates. Should I do a partial water change? Will that interfere with the cycling process? If I do need to change out some of the water, how much should I change?

Today, the ammonia was about 1.5 ppms, so I did not add any ammonia. The nitrites were at 4.0 to 5.0 ppms. They have been at that range for about a week and a half or so. The nitrates were at the highest level that the test can show (150-160). I am using the API Master Test kit.

I will continue to add ammonia to keep the levels above 1.0 ppm.

Any suggestions? And thanks for your help!


Hi Sharon,

It’s perhaps the most frustrating part of fishkeeping, especially when you just want fish now. Cycling is worth the effort though, all your fish won’t die on you.

Your nitrates will continue to rise, it’s a good sign as it means your nitrites are being slowly eaten away as the beneficial bacteria forms. I’d do a partial water change so that you can get the nitrates back down to a readable level on your kit. It’s possible you might need to perform another the next day too if it’s still off the charts. A 50% water change should roughly halve the nitrate levels.

This will give you a better understanding as to what is happening in your tank.

A water change won’t mess up your cycle as long as you are using a dechlorinator. A water change will dilute nitrites and ammonia, so make sure that you dose your ammonia back up to your desired level.

Mr. Sterling,

I did the water change and found that the nitrate level was still very high, so I waited a day or two and did another 15% water change. I use prime water conditioner. The nitrates finally went down. But I think that I may have messed up the cycle. The ph was at the lowest level. I asked someone about it, and they recommended top fin ph increase. I only added a little bit (not enough to bring the ph up to 7.0). Since then, the nitrites are down, nitrates are at a good level, the ph is at about 6.6, but the ammonia is staying at 2.0. It’s been like this for a few days. It’s like the bacteria have stopped eating the ammonia all together, and the nitrites are almost at 0.

Suggestions, again?


Hi Again Sharon!

Sorry to hear about your struggle. In a fishless cycle, I prefer to use baking soda than chemicals (there is no guarantee how they will react). I do not have any experience with Top Fin pH increase but I do hope it didn’t crash your cycle.

What’s the temperature of your tank? At a pH of 6.6 ammonia should still be processing ammonia, but much more slowly. For it to be static, something has happened to your beneficial bacteria.

If you want a faster solution, I highly recommend signing up to one of these online aquarium communities You’ll get a much quicker reply from a wide range of people, it’s possible someone has experienced and overcome the exact same problem as you!

Hey there, thanks so much for this helpful information!! What would you recommend the starting point for ammonia levels in a 20 g tank? I’ve just started the cycle today and added 3.15 mL ammonia plus 20 mL Fluval bio enhancer. The ammonia measures at approxinately 2-2.4 ppm. Should I add more ammonia or is this enough?
Thank you!

HI Ian,
I just found your blog and could use some help. Here is my situation:
I am on day 19 of a fishless cycle, I have used Prime, Stability and fish food and Easy Green fertilizer. My tank is a planted 10 gallon and I have a betta in a bowl that I want to put in it. I used 8 gallons tap water which is soft and 2 gallons RO water because my tap has a high PH so it was recommended I add some RO to help lower ph. because of the betta. My tap water is PH 8.4 The temp was 78 but I raised it to 82 in the tank. PH is 7.2 7.4

Because of too many different ways of cycling and sources online etc that sometimes leave out info I feel like I have not done my cycle the correct way when using these products. For some reason I never ran across info on using bottled Ammonia until the day I set up my tank and my plants had arrived so I had to use fish food.

I used Stability and Prime the first day as directed and put in fish food. I put food in daily and used the stability as directed. (later I read that you don’t need daily fish food when using stability only a few days a week)

I did a water change 10-15% on day 7 adding my last dose of Stability and Prime. (recommended by an online video with water changes)
I keep testing and adding food daily- have dosed Easy Green once a week.

Readings on Ammonia have NEVER gone above .50 Nitrites have never gone above 1.0 -2.0 and Nitrates have gone as high as 160 ppm on day 12 (so I did another water change adding Prime and Stability)

Since then I have algae growing at least 4 kinds, 6 to 10 snails most of which I got rid of but I have 3 currently in the tank, lots of gross fish food on the substrate. The Octopus plants seem to be growing and the A Sword (maybe) hard to tell. There are Anubius and Crypts as well not doing great but okay.

The tank has LED lights that I ran 8 hours a day but have cut to 6 because the room is semi lit during the day from the windows (I do keep the blinds mostly closed)

Day 16 I put in some water for evaporation and used Prime in it then read somewhere that you don’t need prime in a fishless cycle (I think on a Seachem forum) so by now I am frustrated that I am ruining everything….but your blog is reassuring:)

Readings that last 3 days are Amm-0, Nitrite 0, Nitrate a color between 20-40. Is it only because of the Prime being added or is the tank cycled? It’s only day 19 and having never read an Ammonia reading above .50 I hesitate to believe it. Don’t you have to have ammonia of at least 2 or 3.0 for a proper cycle? I feel like I need to drain the tank and start over with liquid ammonia and Stability and no Prime until my last water change before I put the fish in.

I am sorry this is long and you get this stuff all the time I am sure but I really need help from someone. Real help.
Thank you!
Rebecca Rollins

Hi Rebecca,

Thanks for being so descriptive.

The good news? It does sound like your tank is actually cycled.

The bad news? Your tank may only be able to process .50 of ammonia in a 24 hour period.

The amount of ammonia is determined by the amount of fish food you add. If you only added enough fish food to introduce .50 of ammonia, then that’s all the beneficial bacteria will be able to process. Because there is no more food than this, the beneficial bacteria will not grow in number to process more than this amount.

The reason people add up to 4 ppm of ammonia is because this allows the beneficial bacteria to process up to this amount in a 24 hour period (in a fully cycled tank). This means that when you add your fish, assuming you have stocked your tank correctly, the beneficial bacteria should be able to accommodate the amount of waste your fish produce.

It is for this reason that it’s better to have more beneficial bacteria than less. The bacteria will die off until they equalize with the amount of waste your tank produces on a daily basis anyway.

You can test this by adding ammonia to your tank (2ppm) and seeing how the tank responds. Based on what you are saying, I’d be doubtful that your tank could process it in 24 hours. However, you can just keep dosing this amount of ammonia until it IS processed. Sure, it’ll likely take another week or two but you’ll know for sure your tank will be able to handle your betta.

As for seachem prime, if anything, there is a concern that it can give a false positive for ammonia. It doesn’t remove nitrite or ammonia from your tank. It just temporarily renders them harmless. Using seachem prime will not affect your cycle. In fact, for a fish-in cycle, seachem prime often plays a vital role in keeping fish alive.

As for the algae, if it’s brown and sludgey, it’s likely diatoms, and appear in most new tanks. These will go away on their own. If it’s anything else, it’s likely that your nutrients are out of balance – perhaps too much light, etc. This will be a balancing act on your part.

So don’t stress, everything sounds good. And please don’t drain the tank and start over!

Thank you for your response! I understand and agree with what you are saying. Should I use liquid ammonia then? I don’t have any so I assume I should keep putting food in until I get some and should I vacuum up the old food with a water change (because my PH did go down today to 6.6 from 7.4) Someone did suggest that I should try using some frozen food instead of the flakes and see if I can get the ammonia up. Would that work too? It’s just hard to measure how much food to use apparently because I did use 3 or 4 pinches of flake food to start then used less as suggested when using food but I guess you need way more than that. I see that I did not mention that I am using a sponge filter does that make a difference?

Not a problem Rebecca, let’s try and get this whole cycle sorted for you.

6.6-7.4 is a massive drop in pH, one that would certainly stress fish if they are in your tank. I’d personally test your the KH of your tank using a KH test kit. KH helps prevent pH swings. I’d also test your tap water too. If your tap water reads higher than 4 dKH, a water change will be all that’s needed to improve your KH. If it’s less, you may have to use another product such as alkalinity buffer, aragonite or crushed coral. I’m actually in the middle of writing up an article on KH as we speak.

I personally like to use liquid ammonia because it allows me to dose a specific amount, and I can see how the tank reacts to that exact amount. However, you can also use a frozen uncooked shrimp (place it in a filter media bag or nylon stocking to prevent it breaking up) – a single decent sized shrimp should be enough. But again, you won’t know how exactly how much ammonia it will give off. With that said, I know many fish keepers who successfully use this method to cycle their tanks. Whichever you choose, you’ll be okay.

I’d definitely recommend vacuuming up the old food with a gravel vacuum if you go down this route. I’d wait a day or two after adding the shrimp though.

Just had a thought on your algae problem too – your flakes very likely contain phosphates, which is a popular “food” among certain types of algae.

A sponge filter shouldn’t make a difference. In fact, biological filtration (removing ammonia and nitrites) is where sponge filters excel due to the amount of beneficial bacteria they can hold.

Hi again!
I’m on day 14 of fishless cycle. Nitrites showed up on day 8. They were 0.50 ppm on day 8, then spiked to 5.0 ppm two days later. Then Nitrates showed up on day 11 at 40 ppm, at which time the nitrites dropped to 2.0 ppm.
Today on day 14, the ammonia is getting eaten up nicely daily, I have to add more every day. But the nitrites have been stuck at 2.0 pppm for a few days. Is that normal even though the nitrates are in there too?
Thanks for your help!!

Way to go, Rosie!

That sounds like good progress. Are the nitrates still going up even though nitrites are remaining at 2ppm? If so, I’d just wait and monitor all of your parameters for a few more days.

Well, my nitrates today are at 5.0 ppm. Weird. Perhaps I did the test wrong the first time! I will check again tomorrow to be sure.
As of now, nitrites are still 2.0.

I did add 4 L of water to tank yesterday because it had evaporated a lot since i started, perhaps that is why nitrates dropped?

Will check again tomorrow! 🙂

I’d give it another three days of testing, just to see what’s happening. Based on what you have said, it doesn’t appear like anything is out of the ordinary. It’s just a darn slow process.

Adding freshwater will certainly dilute the nitrate, causing a lower reading – this is the entire reason we perform routine water changes.

Thanks for the reassurance! This is a slow process haha! Pretty cool though learning about it and I can see now why I always killed fish in the past! Sigh…not this time!
Thanks again!

Hi Ian,
So my nitrites and nitrates still aren’t moving. Both stuck for days. The nitrates are there but don’t seem to be multiplying. The last four days I have tested each day and nitrites are at 2.0 ppm and nitrates are at 5.0 ppm. I have to add ammonia daily because the bacteria are eating it almost all up each time. What would be stopping the nitrates from going up?

Hi Rosie,

This has me stumped. Ammonia doesn’t just disappear. It has to go somewhere. Are you shaking your nitrate test long enough? Just in case the nitrate test has gone funny, give bottle #2 a shake for 3 minutes.

Then follow the instructions closely:

1. Fill a clean test tube with 5 ml of water
to be tested (to the line on the tube).

2. Add 10 drops from Nitrate Test Solution
Bottle #1, holding dropper bottle upside
down in a completely vertical position to
assure uniformity of drops.

3. Cap the test tube and invert tube several
times to mix solution.

4. Vigorously shake the Nitrate Test
Solution Bottle # 2 for at least 30
seconds. This step is extremely
important to insure accuracy of test

5. Now add 10 drops from Nitrate Test
Solution Bottle #2, holding dropper
bottle upside down in a completely
vertical position to assure uniformity
of drops.

6. Cap the test tube and shake
vigorously for 1 minute. This step
is extremely important to insure
accuracy of test results.

7. Wait 5 minutes for the color to

8. Read the test results by comparing the
color of the solution to the appropriate
Nitrate Color Card (choose either Fresh
water or Salt water). The tube should
be viewed in a well-lit area against the
white area of the card. The closest
match indicates the ppm (mg/L) of
nitrate in the water sample. Rinse the
test tube with clean water after use.

Shaking is super important for accurate results. Does this help with the reading?

Two days later, I am doing the test right – thank you for that because I actually wasn’t shaking enough before – but it still is reading the same! I’m stumped too. Nitrites 2.0, nitrates 5.0. Ammonia is being added and disappearing to about 0.25 daily, so not completely disappearing but mostly. I don’t know what is the issue here haha!! I know the test kit works because the first time nitrites showed up, it was a different colour and lower number. And the first time I tested and found nitrates it was actually 40! I did add a bit of water which makes sense for the lower number at first, but it should have risen by now I would think 7 days later. So. What to do, what to do. I could do a water change maybe? Wait longer? Could there be something slowing down the growth of nitrates? I made sure to condition the new water before adding. The tank temp is 23 degrees celsius. Ammonia is disappearing so I know the bacteria is in there and working. Any ideas??

Thanks for your help!

Hi Rosie,

Can you list everything you have in your tank? Including the filter and filter media? I have not come across a tank before where despite ammonia decreasing, the nitrite and nitrate remain stagnant – the most common scenario is the test not being performed correctly, but you seem to be all over that.

A water change shouldn’t harm your cycle. You could do a 25% change and record your nitrite and nitrate levels before and after. Also, test your tap water too, before you add it – sometimes this can already contain levels of nitrates, adding to the confusion of the cycling process.

Hi Ian,
So I have only fishtank gravel, a couple fake plants, and a little ornamental castle in the tank (bought at pet store, it is safe for tank). No special live plants or rocks or anything. I’m using the Api freshwater test kit, brand new.

Measurements today:

Tap water:
pH is 6.2
Nitrites 0.0
Nitrates 5.0

Tank water:
pH 7.2
Nitrites 2.0
Nitrates 5.0
Ammonia 0.0

I’m wondering if the nitrites are actually way above 5.0 ppm. The two colours of purple are so close its hard to tell. Maybe my nitrites are off the chart and that’s why it seems like they aren’t coming down? I’m wondering also if my nitrate solution is no good. My tap water reads the same as the tank.
So I’m going to top up the ammonia again like usual. Tomorrow I’m going to take a tank water sample to the pet store and ask them to test it and see if they get same results. Then I’ll go from there!

I am on well water, not city. Our water is super clean. Not sure if that matters.

Sheesh this is quite a process! 🙂

Hi Rosie,

An easy way to see if your Nitrates are way off the chart is to do a water change and re-test. a 50% water change should see your nitrates lower considerably, to the point you should easily identify the color change on your test. Alternatively you could add 50/50 tankwater-distilled water to your tube when testing, this will approximately half the reading. Double it to get the true reading – good for when your nitrate levels are off the charts.

From here you can wait and see if the nitrates increase again, and at what rate.

It looks like it’s possible your 5ppm nitrates is from the well water rather than forming as a result of the cycling process. Nitrates are not uncommon in well water, it usually comes from decomposed plants and fertlizer runoff.

Also, well water can prove to be problematic. – do you have it regularly tested for contaminants? A member of my old fish club who had recently moved to the area was on well water and had an issue with pesticide contamination. The only reason it was discovered was because he was unable to cycle his tank despite being in the hobby for 10 years and successfully cycled many before. Of course this is only anecdotal, and I just mention it because while municipal water supplies (tap water) have to conform to strict testing regimes, in my state at least, it’s on the owner to have their own well-water tested.

Unfortunately, those on well water often have a more difficult time than those on tap water. I have my fingers crossed for you that this isn’t an issue.

Hi Ian,
So I did a 50% water change and nitrites are still dark purple! They were not 2.0, they have been way up above 5.0 off the chart. The ammonia is going to 0 now each day. How much do you recommend putting in the tank to keep the bacteria happy? And should I do another water change to get nitrites down further or just wait a bit and see if this kickstarts the nitrates growth again?

Hi Rosie!

Woohoo! It might not sound like it, but that’s good news. It explains that the ammonia is being converted as usual.

High nitrite shouldn’t stall a cycle. Personally, I’d try get the Nitrites down to a readable level. This way you can see what is actually happening in your tank.

As for how much ammonia to keep adding, 2 ppm should work out to be fine.

Hi Ian!

So yesterday I did two 50% water changes, one right after the other. I wanted to get nitrites down to readable. Finally did get to 2.0 ppm after the second change.

Guess what! Today my nitrates have finally multiplied! Yay!

My readings tonight are ammonia 0, nitrites still high at either 2 or greater than 5, and nitrates at 40 or 80 Those two shades of purple and red are so close its hard to tell, but nitrates definitely are up finally!

I dosed with ammonia again like usual. Now do I just wait and hope those nitrites start to drop?


Yay Rosie,

Woooo! That must be a relief. I won’t celebrate too much because I don’t want to jinx it, but this is all hugely positive.

I probably wouldn’t have done the water changes consecutively, but if it works, then it works!

Now everything looks normal, it’s the dose with ammonia and wait game. It could take two weeks, so you’ll need some patience. But before long you should see some downward movement on the nitrites. Just be mindful that it’s possible your nitrites have not peaked yet, and may continue to rise before they finally dip. This is normal. If your nitrites or nitrates exceed the chart again, use another water change to bring them down. It won’t affect the cycle, like before, but it will allow you to see exactly what’s happening.

Hi Ian,
So my mitrates seem to be rising slowly, the red is darker today than it was three days ago. Nitrites seem to be rising still or at least the same, purple is darkest on chart. Like you said though, it may take a bit for the nitrites to peak and drop.

My question is should I be dosing with ammonia every day? Even though nitrites haven’t dropped yet? My ammonia goes to zero every 24 hours and I don’t want the bacteria to starve so I’m dosing daily. But is dosing every day what is making my nitrites go so high? Maybe the nitrite-eating bacteria can’t keep up? I’m putting in 3.5 mL of ammonia daily, which brings it up to between 1 and 2 ppm. Never higher.

I guess if real fish were in there, they would be emmitting ammonia daily as well so it should in theory be ok right?

In your instructions, it says not to dose daily until nitrites are as low as ammonia, but my ammonia had been going to zero daily for quite some time. So I was a bit confused as to what I should be doing.

Will wait a few more days and cross fingers these nitrites finally drop!!

Thanks! 🙂

Hi Again Rosie,

All of this sounds perfectly normal. And yes, you keep dosing daily – you don’t want the first bacteria to starve. The second bacteria will establish itself to a point where it can eat all the nitrite in your tank. Again, if ever you are concerned you can do a water change to lower the levels so you can monitor them, although it isn’t at all necessary.

I can see where you got confused in the instructions. I really appreciate this feedback – I’ll attempt to make them clearer for others.

Hi Ian!

Well, day 31 and we are finally cycled!! Nitrites hugely dropped yesterday and today Ammonia and nitrites are both reading zero. Yay!!

So tonight I will add a full dose of ammonia, and if tomorrow its all at zero again, is that the time to do a big water change and add fish? Eeeek!! So exciting ????

I wondered your opinion, if I have been keeping the tank dosed at between 1-2 ppm ammonia, how many fish do you think I should start with? It’s a 20gallon tank. We were thinking neons and guppies to start.



Wooo Rosie!

That was an effort! Congratulations. It will be worth it. Neon tetra are a schooling fish, so minimum size number is 6 (although more is better) you could do 10 or so and 3 guppies? Honestly, the exact amount is up for debate here, if you were to ask 5 different people, you’d get 5 different answers. It never hurts to ask the place you are buying them from for a second opinion. Just make sure you stay on top of your water maintenance and testing. You’ll soon get the into a rhythm as to how often to test and maintain.

Just make sure that your nitrates are way down, as while these are harmless in small amounts, then can prove to be toxic if they get out of hand.

Also, I just want to confirm your tank has a filter and heater? When I went back and read what’s in your tank, I noticed you didn’t list them?

Hi Ian,

Thank you for the advice about the fish! I think we’ve decided on guppies and cory catfish to start, then add tetras later once tank is more established, as I have read they can be quite sensitive to the ups and downs of a new tank.

Yes i forgot to mention, but i do have heater and filter as well!

I had a question about pH. My tap pH is 6.2. But it seems to rise quite high once in the tank, up to 7.8. Then it tends to steadily slowly decline. Today its down to 7.2. I know there are a lot of factors that could be at play and pH could fluctuate even in 24 hours up and down. How do I keep it stable? Why does it go so high after being in the tank? It is just from all the chemical processes going on? Will it harm the fish if that happens when they are in there?

Thanks again, you have been so helpful!

Hi Rosie,

You are probably sick of hearing about the dangers of fish (they are darn sensitive) but pH swings can be serious. Because pH is measured logarithmically, a pH of 6 is 10 x more acidic than a ph of 7. A ph of 5 is 100 x more acidic than a pH of 7, and so on. So while the change in numbers might seem small, the change in pH is hugely noticeable to your fish.

It sounds to me like your water might also have a low KH, which helps prevent pH swings. I recommend reading my KH guide first and I’ll answer any questions you have after, I’d love feedback on if the guide is easy to read and understand, I just completed it last week. Unfortunately, a test kit for KH isn’t included in the API master test kit and will need to be purchased separately. It’s a funny one in that not everyone needs it, so they don’t include it in the master test kit.

Hi Ian:
Thanks for all this great info. . . I really appreciate it! There are so many conflicting opinions online that it’s hard to know what is correct. Anyway, I’ve been trying to cycle my 10 gallon tank (fishless). I’m following your directions above. I added enough ammonia in the beginning to get about 2ppm. . . is that correct? It’s been 17 days and the ammonia isn’t dropping. . . and no nitrites. I’ve been testing every day. the PH is good. I did a 20% water change a couple of days ago on the advice of someone who said maybe there’s too much ammonia in the water. Can you tell me what I’m doing wrong and what I need to do now to get it cycled?

Hi Lezlee,

If it’s been 17 days since you initially added 2 ppm and have not added more then something is certainly amiss. Have you tested your nitrites and nitrates, just to check what’s happening there?

Also, what is the ammonia reading since the water change – the water change should have diluted the ammonia levels.

2 ppm isn’t too much ammonia to kickstart a 10 gallon tank cycle. I have personally used this amount for my nephews tank. Something else is amiss that is preventing your beneficial bacteria from establishing.

Unfortunately, given the limited information you have provided, narrowing down the exact cause will be difficult.

First, what are all your water parameters: PH, Ammonia, Nitrate, Nitrite?

Next, is your filter set up correctly and does it contain filter media?

Did you dechlorinate your water prior to adding it? Chlorine kills bacteria, good or bad.

Next, what is the temperature of your water?

What else is inside your tank?

Finally, and this is perhaps the most unlikely point of failure, but I have seen it before – is your aquarium test kit within it’s expiry date?

I generally reply to comments once a day so if you need a faster response I highly recommend posting your question in one of these friendly online communities with the information I asked for included, you may find someone has experienced the exact same problem as you and can give a quick solution.

Thanks for the response! So here is everything you asked for:

Ammonia is 1.0. . . but I must not have gotten enough in the tank in the beginning. . . because it has read 1.0 from the beginning (18 days ago). Your directions said to put 1/2 tsp for 10 gallons to get ammonia to 2.0. But I ended up putting in 1 and a half tsp because it wouldn’t come up to 2.0 and then was afraid to put in anymore.

Nitrites are 0
Nitrates are 0
PH 7.6
Temperature is 80 degrees

I did de-chlorinate the water before I put it in, and all water I add
The tank has 2 fake plants, one fake driftwood piece, 1 ornament, larger gravel (looks like little stones), a heater, and the filter. The filter is an Aquelon that has a white meshy filter in it, as well as a long-ish rectangle grey looking thing that says it’s supposed to help remove ammonia.
Oh, and I checked the expiration dates on the tests and they’re 2023. I just don’t know where to go from here. Thanks again for helping!


Hi Lezlee,

As per the article:

If your ammonia readings are less than the above levels, add more ammonia and re-test.

2ppm is the minimum level I recommend for a tank your size when first dosing to kick-start the nitrogen cycle.

Even so, I would have expected at least some of that 1.0ppm of ammonia to break down by now. Based on the information provided, I cannot see anything wrong here.

I’d try raising the ammonia to 2 ppm and keep testing. If that doesn’t work, I’d try using a shrimp in a nylon stocking to introduce ammonia, just in case there is something wrong with your batch of ammonia – this will eliminate the ammonia source as the problem.

Unfortunately, when something does go wrong, you just need to keep narrowing things down until you find the problem.

Hi again:

I’m so excited! I put more ammonia in the tank to bring it up to 2.0 ppm on Nov 9th, per your suggestion. This morning my ammonia is reading .25, and nitrites at 2.0 so it looks like it has started to cycle! My ph is 7.6 so that’s good too. I put in a half dose of ammonia, per your instructions in the article, and will test each day to see when the nitrites drop and continue to follow your directions. When it’s completely cycled and ready for fish, is one fish for 10 gallons enough to feed and keep the bacteria going? I have one fish in a 3 gallon tank, and I plan to put in the 10 gallon when it’s ready. The reason I have it in the 3 gallon tank is that I have lost a few fish because a pet store sold me a fish that turned out to have ich after a few days. Of course the other 2 I already had got it too, and the 10 gallon tank was infected with it. So now I want to put new fish in this smaller tank for a couple of weeks to make sure they are healthy before putting them into the bigger tank. (I did empty and clean out the infected tank before trying to cycle it). One last question, Will the small tank ever be cycled? I’m treating it with one dose of Prime every day for the little bit of ammonia it has (.50 ppm) but wasn’t sure if tanks that small ever cycle. Thanks again for your help!

Hi Lezlee,

Congratulations! That’s awesome to hear. Nothing like seeing some progress 🙂

If you have somewhere for the beneficial bacteria to live, you can cycle a tank that small. It’s a similar process to larger tanks.

The beneficial bacteria will adapt to the amount of waste your fish produces. The reason we try to grow more beneficial bacteria than is needed is so that the bacteria will “starve” and die back to the right amount rather than attempt to “grow” to the right amount, which can take time during which your fish will be exposed to these nasty chemicals.

A single fish should be fine, but even so, it is recommended you keep an eye on your water parameters for the first week, just to make sure everything is Ay-okay. After that, you can reduce testing to your maintenance schedule.

Hi again Ian:

So my 10 gallon tank looks like it’s progressing, but the nitrites have stayed at 2.0 for 6 days. The nitrates went from 5 to 160 in 2 days. Yesterday I put in a half dose of ammonia and it read zero today, with the nitrites still at 2 and the nitrates at 160. The directions say when the nitrates show up you should add a half dose of ammonia every few days to keep it at 1.0 or more. Since my ammonia is 0, should I add the half dose every day now?

Also, about my 3 gallon tank. (1 fish that’s been in the tank for 4 weeks and doing well). The ammonia reads .5 every day with no nitrites. So every day I put in one dose of Prime. Should I be doing any water changes at this point, and is having ammonia at .5 every day and no nitrites showing up normal?

As always, I really appreciate your help. Your directions and explanation of the process are the best available on the internet!


Hi Lezlee,

I’d do a water change so you can see what is actually happening – since 160 is the highest reading on the card, you won’t be able to test any further movement. I’d perform a 50% water change, to get your nitrates back down to readable levels. I’d do one each day for two days. This should get them back down to 20. Make sure you dose back up with ammonia! I’d be dosing daily.

The reason I suggest this is so that you can see exactly what is happening in your tank. As it currently stands, we do not know if your nitrites are still being converted to nitrates. Getting them back down to readable levels will help determine where the bottle neck is. If the nitrites are remaining at 2 but nitrates keep growing, then it should just be a matter of more time.

As for the 3 gallon, your fish should be producing enough waste to have at least started the cycle by now. Is there any nitrates in the tank? There is even a possibility that your tank has already cycled – Seachem Prime converts ammonia (harmful) into ammonium (harmless). The problem is that this ammonium can still be picked up by test kits as ammonia. It’s not unheard of for seachem prime to give a false positive for ammonia with liquid tests such as API. If you are reading nitrates, but no nitrites then this tank is cycled. You can confirm this by waiting 72 hours and retesting for ammonia. Fingers crossed that this is the case!

Hi again:

I did a 50% water change 2 days in a row, like you suggested. My readings are now at 0 ammonia, 2 nitrites, and 5 nitrates. So it looks like there isn’t enough of the bacteria that eats the nitrites. . . ? Do I just keep daily dosing the ammonia and wait for the nitrites to go down?

And my 3 gallon tank continues to be stubborn. Ammonia at .75 (kinda in between greens), 0 nitrites and I’m not sure if there’s maybe a trace of nitrates. . . it’s just a tiny bit darker than the palest yellow, but not orange-ish at all. I’m still putting one dose of Prime in every day and my fish is doing great. Do I need to be doing anything other than what I’m doing for either tank?


Hi Lezlee,

If all other water parameters are correct, there is nothing left to do but keep doing what you are doing and wait. Please update me in 5-7 days with what is happening!

Well, It’s been 3 weeks since I last posted and I’m still struggling. This morning my 10 gallon tank readings were ppml ammonia, 5 nitrates and .25 nitrites.. The ammonia stayed at 0 for a while but rose to 1 for a couple of days and now 2. At one point the ammonia was 0 and the nitrites were .5, so close but it never got to 0 and 0. Then the readings started going up and down. . . nitrites anywhere from .25 to 5, and nitrates from 1 to 5. Clearly I’m doing something wrong. . . it’s been 7 weeks. How much and how often do you think I should be putting in ammonia now?

Also, my 3 gallon tank sometimes reads 1 and sometimes reads 2 ammonia. Still no nitrates or nitrites. Have been putting in 1 or 2 doses of Prime every day and the fish seems fine. Seems like there should be nitrites by now.

And one more question, please. My son has 1 betta in a 3 gallon tank just like mine. The ammonia is almost always 4 ppm, sometimes even 8. He puts the appropriate number of doses of Prime in every day. I just wondered if this amount of ammonia is normal for a betta. . . the fish seems fine. He does water changes, but maybe not often enough? My single fish never makes that much ammonia.

Thanks again for all your help. . . I really appreciate it!


What is the pH and temp of the two tanks? Are you monitoring this as well? Could you confirm your testing, readings on nitrates generally don’t go up and down, not with what you have in your tank anyway. I still recommend keeping ammonia up at 1 ppm with a daily top up if it drops under until nitrites are 0. Are you able to get someone else to confirm your tests?

Regarding your sons tank, IMO a 3 gallon is too small for a betta and without constant water changes, waste is going to build up quickly regardless. Another possibility is that your son is over feeding. The more food, the more poop, the more ammonia.

Thanks, Ian. I’ve actually been out of town for 2 weeks so my son has been doing the testing for me (he’s 22, not a kid). I’ll ask him to test for PH on both tanks, and check the temps and let you know. 🙂

Thanks Lezlee,

I hope we can get to the bottom of this mystery. It would be great if you can return home to a cycled tank!

Thanks…that would be great! But now I have another problem. Apparently the platy in the small tank has had babies….my son says he only sees 3 so I dont know if she ate some of them, because he saw her chasing one…looked like she was going to eat it. So he put her in a temporary (VERY small just for transit,etc) by herself. I told him to watch her to see if she has more babies. We don’t know what to do. Should we put her in the big tank alone and dose it with the appropriate amount of prime until it finishes cycling? I hate to lose all the babies, but I don’t want to lose the mother either….what should I do?


Hi Lezlee,

Unfortunately, it doesn’t look good for your babies – fry are much more sensitive to water parameters adult fish. I couldn’t guarantee their survival in a fish-in cycle, much less the mothers. Are you able to take the fish to a pet store in the mean time?

So you’re saying even if we continue to treat every day with the Prime the babies probably won’t survive? If I wanted to try to keep them, would I need to do anything special for them? Or do you think I shouldn’t even try to keep them alive?

It’s hard to say, the fish-in cycle process is tough. I know it’s a heartbreaking thought and I wouldn’t wish your situation on anyone. They *might* make it through, but short of moving them to a cycled tank, there is no guarantee you can save them. The cycling process is tough, it’s why the old fashioned way used hardy fish, like zebra danios for a fish in cycle, and even these often wouldn’t make it through.

Well my son went out and bought a 5 gallon tank to put Izzy in (the mother). We were afraid to put her back in the 3 gallon tank with the babies since she looked like she was trying to eat them. And the 10 gallon tank isn’t finished cycling, so we didn’t want to put her there. (It would take a lot of Prime every day). So, we’ll have to do the fish in cycling with Prime process, like I was trying to do with her original tank. When the 10 gallon tank finally cycles we’ll put her in there (which was always the plan), and the babies too when they get big enough. That is, of course if any of them survive. Izzy did very well with the Prime every day, so I’m hoping she will in this new 5 gallon tank as well. I’m worried about her because she was in the small transport box for a few hours today, then put in the 5 gallon tank, which is bigger than she’s ever been in. But my son did the best he could to make sure the temperature in the new tank was the same as the small transport box, and treated it with Prime. It has a heater and filter too. She has hung in there with me for 7 weeks in an uncycled tank so it will break my heart if we lose her.

We’ve worked hard to get this far and we’ll try our best to keep them all going. I’ll let you know what happens. . . I really appreciate all your help and advice!


Yeah, platy aren’t too bright and can try to eat their kids. It was a good move to separate them.

I hear what you are saying, the whole process has been quite an ordeal for you and it would be amazing if she pulls through. I have my fingers crossed for you.

It sounds like, given the circumstances, your son has done as well as he could. Hats off to him. How did he go re-testing your aquarium to confirm the bouncing nitrates? At the end of the day, this is the biggest issue, the lack of a cycled tank to place your fish in. It would be great to see some progress here.

Yes, getting the 10 gallon tank cycled would be wonderful!

Izzy and the babies made it through the night ok, and they all seem to be pretty active, according to my son (I’ll be home on Sunday, thank goodness, so I can help him. . . now we have 4 tanks to test every day)! He fed the babies flakes this morning that were extra ground up and he said he thinks one or two of them ate a bit. Do they usually figure out eating pretty quickly? Should we feed them a couple of times a day? We were worried about the filter sucking them up, so after looking online we decided to take a fish net, cut it, wrap it around the opening and secure with a rubber band. Hope that will work as long as we need it to. Will it take long for the babies to grow just a bit so they won’t be so tiny?

He was doing the testing yesterday when he discovered the babies, so we both panicked and he stopped testing to go to the pet store for the 5 gallon tank once he saw Izzy try to eat them and we figured out what we should do. But he tested all of them this morning and here’s what he got:

10 Gal: Ammonia 4 – Empty tank
Nitrate 1
Nitrite 1
PH 6

3 Gal: Ammonia 1 – (babies’ tank)
Nitrate 1 or so. . . not orange but a tad darker yellow
Nitrite 0
PH 7

5 Gal: Ammonia 0 – (New Tank with Mother)
Nitrate 1
Nitrate 0
PH 7.6

I don’t know what’s wrong with the 10 gallon, up to 4 on the ammonia again. What do you think about all the readings?

His betta was 4 on the ammonia again, I told him to do water changes more often. The plan is now to move the betta into the 5 gallon when Izzy can finally go into the 10 gallon. I hope this isn’t confusing. . . too many tanks!

Thanks again Ian!

Platy fry will eat the same food as their parents, so he more than likely did see them eat. Ignoring the argument that it’s better to feed a varied diet with live food, they should be fine with this meal.

Twice a day feeding should be fine, you need to remember that any uneaten food (and there will be lots with fry) can affect water quality, which is already balancing on a knife with your fish-in cycle. Any pieces of uneaten food that can be scooped out after feeding is a good thing.

For readings I generally recommend creating a spreadsheet and adding the daily readings, so you can see exactly what each parameter is doing. There are plenty of free apps that will also do this. For this many tanks, it might be a good idea, making it easier to keep tabs.

Adding so many tanks into the mix is making it difficult for me to keep up, although I have double checked my advice based on the comments and I believe we are on the same page.

For the 10 gallon, a pH of 6 is acidic to the point where it can prevent growth if not downright kill the types of beneficial bacteria present in aquarium filters. We want to ideally keep the pH at 7 or higher. This will need to be adjusted and it’s quite a delicate process. Normally, a water change should be all that’s needed to raise the pH however, so if you test your tap water (after conditioning) and find that it’s pH is greater than 7, you can use this. Perform a water change and re-test pH and all other parameters. Based on your previous comments I believe a water change should be all that’s needed. (otherwise we have to go down the road of KH, but that’s a whole other conversation and at this stage I don’t think we need to add to the confusion.) I also want to confirm you are not using seachem prime in the empty 10 gal tank.

A snap shot of the other tanks, everything sounds normal. Although I’m still of the impression that the 3 gallon should be cycled by now if a proper fish-in cycle was performed.

You’ll need to keep up your daily recordings to get a greater understanding of how everything is progressing. I know this is hard while you are away from everything but hopefully we can finalize all this when you get back?

Thanks for your reply. I thought the same thing about the 3 gallon. Over 7 weeks and not a single nitrite has shown up. About the Prime, no we aren’t putting that in the 10 gallon tank. . . just ammonia. But since it was 4 today I told him not to put any in.

My son is graduating from college in the spring with a degree in Business Analytics and a minor in Computer Science. . . the reason I mention this is because he has been keeping a spreadsheet for a couple of weeks. . . guess he thinks that way too! You’re right, it’s the best way to keep track of all the tanks, especially since we now have 4.

One thing I thought about the 10 gallon tank. We decided to take the heater out of it yesterday and put it in the new 5 gallon tank where the mother is, because the aquarium kit he bought came with everything except that and he didn’t realize it until he got home. So the empty tank was without a heater all night. . . he bought another today and installed it. The water cooled to about 72 overnight. Would that hurt the bacteria and cause the ammonia to go up overnight from 2 to 4?

I’ll ask my son to do a water change to try to fix the PH. As I said, I’ll be home late Sunday and it will be good to be closer to the situation and know exactly what’s going on. I’ll post again a few days after I get home with an update.

Thanks Ian!

Tempwise, 72 shouldn’t be an issue. Once it gets under 65˚F growth rate can slow considerably, but it won’t kill the existing bacteria. It’s good you were able to get on top of that so quickly. The temperature change shouldn’t have had any impact on the ammonia spike.

Looking forward to the update!

Hi Ian:

Well, I’ve been home for 6 days now. . . Izzy (the mother in her private 5 gallon tank) and her babies in the 3 gallon tank are all still kicking and seem to be doing well! We discovered we don’t have 3 babies but 5!. They are a week old today. Their ammonia is 1 every day, and I put 1 dose of Prime in daily. Izzy’s ammonia is staying at 0 so far.

The 10 gallon tank today is:

Ammonia – 0
Nitrites – 0..5
Nitrates – 5
PH – 6.6

We’ve been putting 1 ml of ammonia in daily. I know the PH isn’t good. . . I did a water change a couple of days ago but it didn’t seem to do much. I guess I should do another one. . ? The temp is 80. There was actually 1 nitrite yesterday, so hopefully the end is near! Do you think I need to do anything different?

Thanks Ian!


Welcome back Lezlee,

Congrats on the larger than expected family. That’s awesome to hear they have survived.

For the 10 gallon, Are the nitrates increasing? If so, it sounds like it’s almost there. 6.6 ph is on the cusp of two low, if you can increase that your cycle will progress much faster.

The nitrates have been 5 for the last 4 days, and 1 for the 3 days before that. So they have gone up but not in the last few days. I’ll do a water change tomorrow to try to get the PH up.

Thanks again.

Is it the water from your water change that raised the Nitrates to 5? or did the change happen outside of this? Just something to be mindful of.

I was just reading online. . . a bunch of places say to add baking soda to raise the PH level. Is that a good thing to do?


Baking soda raises both pH and KH. If you are adding it to tanks with fish, go slooooooow. You don’t want the pH to increase too quickly. Add a bit, wait, test and repeat.

I looked at the spreadsheet and the nitrates actually went up from 1 to 5 the day before my water change. I was thinking of putting baking soda in the empty 10 gallon tank to try to raise the PH in hopes of moving the cycling along faster.

I’ll let you know how it goes.


Awesome, well if that’s the case then there is some slight cycling action taking place which is a good sign. Increasing the pH to an appropriate level should noticeably improve the speed that the tank cycles. Please let me know how it goes. I am hoping the next update is positive 🙂

Hi again:
My nitrites look like they’ve gone from 0.5 to 1. I’m so confused and frustrated, having been at this so long. I read over your article again. I’m not sure if I should be putting in half a dose of ammonia every day or every few days. Since the ammonia is reading 0 every day, I assumed it was getting eaten by the bacteria and it needs to be fed daily so it won’t die. Is that correct? But then somewhere I read that if the nitrites aren’t going down, it’s because the 1st bacteria has too much ammonia to eat, thus producing more nitrites than the 2nd bacteria can consume.

readings today are ammonia – 0
nitrites – 1
nitrates – 5
PH 7.2 (baking soda helped)

Your advice?


Hi Lezlee,

It’s only been a day since you raised the pH. I wouldn’t change anything yet. You can’t expect results in a single day, especially since you have only just gotten the parameters ideal for cycling. Because of this, it makes it difficult to apply a guide that was designed around having all parameters correct in the beginning, to a tank that has partially completed it’s cycle, with some hiccups like overly acidic water along the way. You won’t have the same milestones.

What you read is correct. And it isn’t a problem. In fact, quite the opposite, it’s expected. Nitrites are supposed to spike before the second bacteria grows in number to accommodate the nitrites being produced by the first bacteria. That’s what the whole cycle is about, balancing these bacteria. As long as you are providing a consistent source of ammonia, they will balance themselves relative to this input. You just have to wait.

I understand you are frustrated, and it’s the cycling part that causes many newcomers to the hobby to give up. But hang in there and I’ll attempt to help to the best of my ability.

Make sure you keep an eye on the pH, as it will decrease over time. Nitrites and nitrates are acidic. Water change or add more baking soda as needed.

Watch the temperature too.

Over the next few days pay attention to what is happening with the nitrites and nitrates, one of the two (or both) will go up. This is a good thing, and means you are back on track.

To help with testing, view the tests outside in daylight, in the middle of the day. It will allow you to better observe the actual color against the chart.

Thanks Ian, I needed that pep talk! I definitely don’t want to give up. I really want to have Izzy and eventually her babies in the big tank so I can start enjoying them. . . then I’ll only have to test one tank and not every day. . . that will be great! I will keep testing and watching and let you know how it goes.

I sincerely appreciate the information and advice you provide here. It’s wonderful of you to give so much of your time sharing your knowledge and experience to help everyone.


Oh. My. Goodness!!

0 nitrites and 0 ammonia for 4 days while putting in a full dose of ammonia every day!! My 10 gallon tank is finally cycled! Now all I have to do is a water change for the nitrates (80). I did want to ask about transferring my fish from the 5 gallon tank to the 10 gallon one. . I think you said one fish would be ok to keep the bacteria going, correct? Even though her readings are zero ammonia and zero nitrites every day in her 5 gallon tank? Just want to make sure. And as I understand it, the amount of bacteria will adjust as I gradually add more fish, correct?

Also, the 3 gallon that the babies are in. . . that tank was started with the mother in it 10 weeks ago. And it has never shown any nitrites or nitrates. The PH is very bad. . .on December 14 it was 7.0, but has gradually dropped to today’s reading of 6.0. I did a water change a couple of days ago and it didn’t seem to do anything to raise the PH. I know that’s not good for cycling but I don’t know what else to do about it. I’m afraid to use the baking soda while the babies are in it. (It worked very well to raise the PH in the empty 10 gallon tank). Oh, and that’s another thing. . it’s ok to put the fish in the big tank that I put baking soda in about a week ago, right?
The 3 gallon tank has a small heater, but with no settings. It keeps it at about 76-77 degrees. Do you think maybe it’s not warm enough? The fish do fine at that temp but maybe it’s not warm enough to cycle? I would like to keep trying to cycle this tank to use to put new fish in for a week or two before putting in the big tank.

Hope you had a nice holiday. . . Thanks again for all your help, Ian!


Congratulations Lezlee, that’s really awesome to hear. It must feel like such a relief!

A single fish, such as a betta, will easily keep the beneficial bacteria going. To put it simply: If her current tank is zero nitrites and ammonia then it too is likely cycled and enough beneficial bacteria to support this fish – they “eat ammonia and nitrite as quickly as it is produced, so quick that you can’t pick it up with a test. If ammonia or nitrite creeps to readable, then there isn’t enough bacteria.

Yeah, it won’t matter if you added baking soda last week The only concern here is if the pH is different from their current tank. In which case you can acclimatize your fish the same way you would when you buy them from the store.

76˚F shouldn’t inhibit the growth of beneficial bacteria at all. Based on what you have told me, I would say the pH is more of an issue, going off how the cycle completed once you rectified the pH in your 10 gallon. It seems plausible this tank is having the same issues with the pH of 6 and it will need to be raised in order to cycle.

I read over your KH guide. . . now I’m really worried that the low PH will harm my babies. I guess I should go ahead and order the test kit. . . ? Nothing has been added or removed from their (3 gallon) tank so I don’t understand why the PH is dropping.


Hi Lezlee,

Aquarium water generally becomes more acidic over time – even if you have not made any changes. Part of this is because nitrites and nitrates are acidic. Most people can stay on top of this with regular water changes, which are enough to balance the KH and pH. However, if your water source has a low KH, you’ll experience more extreme pH swings and will need to balance the KH as well.

Hi Ian:

Yes, it’s a huge relief!

I think I must have been unclear about a couple of things because of so many tanks and fish, sorry. The fish I’m going to put in the 10 gallon (mother) is a platy. She has been in a new 5 gallon tank since the babies were born 2 weeks ago. She has 0 ammonia and nitrites so far. So I wanted to make sure she would produce enough ammonia to keep the bacteria going. (the Betta is my son’s, and I’m leaving that to him now).

And the babies (3 gallon) tank that you think is cycled (that we took the mother out of after giving birth, that’s the one that has been going for 10 weeks).. Could it be, cycled even though nitrates have never shown up? That’s what I was confused about. I guess I could skip putting Prime in for one day and see if the bacteria is still gone the next day. Would they be ok for one day if the ammonia didn’t disappear?

So you said before to go slow with baking soda when fish are in the tank. Do you think it would be better to test the kh and use the thing you mentioned in that article if necessary? (I can’t remember the name of it at this moment)

Thanks Ian.

Hi Lezlee,

I’ll answer both your comments here:

Absolutely, ignoring that platies are considered to be best kept in groups, a single platy will produce ammonia and the beneficial bacteria will balance out accordingly.

Re: 3 gallon. If nitrates are not appearing, then the tank isn’t cycled.

I think your son’s idea is best. If the tank is cycled, they will be fine in a tank that size. After all, in the wild, their home is much bigger than 10 gallons.

As for when to add the mother, it all depends on the growth rate of the babies. Depending on conditions food etc, they can grow at different rates. The rule of thumb is once they are big enough that they won’t fit in mom’s mouth. It’s possible this could take up to 2-3 months, or much sooner, you’ll have to make a judgement call here.

In an empty tank, baking soda is fine. The only reason I recommend Alkalinity buffer is so that it’s slightly more fool proof. Beginners can easily calculate how much they need, so as to not cause rapid raises that will shock their fish. Baking soda is a more trial and error as to how much you should add. But it still works!

Happy new year!


Thanks. That’s what I thought about the 3 gallon. . . but I just wonder why after 10 weeks no nitrates or nitrites have ever shown up in tests. . . ? The ammonia always stayed at 1 or 2 when the mother was in it. . . with the babies it stays at 1.

So I’ll put the babies in the 10 gallon tank tomorrow, after a water change. Should I do a 50% one to get the nitrates down from 80?
. I didn’t realize Platies do better in groups. . . but now I have a group of them . . . lol! I’ll check in with you in a while after the babies have settled in the big tank and let you know how they’re doing.

Happy New Year!

I think the low pH has something to do with it. Your larger tank was experiencing similar, when we first started troubleshooting, right? Even so, I am puzzled as to why you are not noticing a spike in ammonia. Unless you use a filter media that removes it, it should begin to increase.

I think the first step is to increase the pH and then begin trouble shooting from there, adding ammonia manually like you did on your 10 gallon.

On the 10 gallon, I’d perform a water change. Don’t forget to acclimatize your fish due to the pH difference before adding them.

Ha, yeah you lucked right into that group of platies! Just be mindful that 6 platies is a high bioload for a 10 gallon. Once they are fully grown you’ll need to keep an eye on your water parameters closely and perform maintenance as per your tests.


Sounds good, I’ll try to raise the PH and start dosing with ammonia after I take the babies out. The filter is actually very small with carbon inside some mesh.

I’m glad you mentioned about having 6 platies in the 10 gallon. I thought I could put in a couple more fish later, but it sounds like that’s a bad idea. I think somewhere down the road I’ll upgrade to a 20 gallon anyway. I’ve learned so much from you. .. now that I know the cycling process pretty well I think it would be nicer so I can add a few more different kinds of fish.

I can’t thank you enough; and neither can my fish! I’ll update you in a few days.


For acclimatizing, I am a big fan of the “drip acclimatization” method. I have not written a guide on this as there are plenty of great guides that take you through the steps a quick google away – it’s a pretty simple process.

Ha, let’s get your remaining tanks cycled first so we can guarantee that when your 20 gallon comes along, you’ll be able to take it from start to finish without any issues.

You should be able to catch your fry with your fish net. If they are extra small, and you have a coarse (larger holed) fish net, you’ll need to be careful that they don’t get stuck. If in doubt, a baby-brine shrimp net will do the trick – it’s essentially a really fine fishnet designed for capturing tiny critters.

Oh, one more thing, sorry. When I acclimate the babies, should I maybe put them in my fish bucket with some of their water and add some of the new tank’s water a couple of times? I guess the fishnet won’t hurt them if I’m careful?


Oh absolutely. . . I won’t be upgrading to a 20 gallon for a while. You’re right, I need to get the others cycled first. And I probably will still be asking you questions when I do the 20 gallon one later on. . . lol!



I appreciate that!

One thing I totally forgot to ask you, and probably important, is that a white cotton-like substance has appeared on the ornaments in the 10 gallon tank. Again, I’ve read conflicting things about it. Some say it’s harmless and others say it’s not good. Do you know what it is and if it will hurt my fish? Don’t want it to hurt the babies!


Hi Lezlee,

While we largely focus on the benficial bacteria during cycling, there are “non essential” bacteria that are also fighting to find balance in your tank. This can result in all sort of oddities such as white cloudy water, gooey brown sludges and white slimes. Unfortunately, without paying attention to what triggered, these can be quite hard to identify the cause in hindsight. Can you confirm it has appeared during cycling? If so, and it was my own tank and I was unsure of the exact thing I was looking at, I’d remove the ornaments, bleach dip, wipe off the gunk, wait a few hours for the filter to work, retest parameters then add my fish.

Thank you. . . so I just did a 50% water change in the 10 gallon . . . the ammonia and nitrites are still 0 but the nitrates are still at 80. I don’t know how to get them down. I can’t put the babies in there with that much nitrates, correct?


I’d be hesitant to put babies in a tank with nitrates at 80. fry are much more sensitive than adult fish. I’d do another 50% water change tomorrow and re-test. Don’t forget to keep up your ammonia dosing.

Sorry to keep posting, but I always forget to mention things.

I had some new aquarium ornaments, so I rinsed those really well and put them in the 10 gallon instead of waiting for the filter to work on the ones I had bleached. . . I wanted to get the babies moved today. But of course the nitrate problem didn’t let me do it anyway. I also wanted to mention that the babies’ tank read 0 PH today! I did the test twice to be sure. So I really want to get them out and try to raise it. How long after putting baking soda in a tank would you have to wait to put a fish in it?


I don’t mean to say you are doing something wrong, but I would suggest rechecking your pH test. A pH of zero is pretty much hydrochloric acid. If your babies are alive, it’s not zero.

I’d wait until the pH had stabilized from the baking soda addition. You can test this hourly, after two hours or just wait until the morning.

Hi Ian:

So the 5 babies have been in the 10 gallon cycled tank since yesterday, and so far they seem happy. (I did water changes till the nitrates went way down).

I’ve been meaning to ask you your opinion about changing filters. Some say don’t change them until they are falling apart because of the bacteria in them. Others say monthly or at other intervals. Just trying to understand how you don’t lose all the bacteria when you put new ones in.

Speaking of filters, the one in my 10 gallon has been there for over 2 months while cycling. . . I rinsed it in the aquarium water when I was changing it and as soon as I touched it, the white part just kind of stretched out in a long piece, kind of like cotton does when you pull it apart (only wet and very easily stretched). I actually had to push it back in to keep it in the filter. . . Is that normal?


Hi Lezlee,

That’s awesome to hear your fry have settled in.

You will absolutely lose the beneficial bacteria when you swap out the filter. Especially if your tank relies on the foam in this filter for a biofilter. You can expect your tank to crash if not done correctly. This is why those “disposable filter cartridges” that many big brands are guilty of pushing are actually the worst thing for your aquarium. The razor blade business model should not apply to aquariums. Locking yourself into buying disposable filters for a quick buck, at the cost of fish health and lives is disgusting.

If you have a disposable filter, and the mechanical filtration looks like cotton wool stretched out, these are designed to fall apart in the hope that you’ll replace them. My recommendation is a biomedia (say ceramic rings) and mechanical filtration combo (sponge and if required, filter floss for clarity). If your filter doesn’t have room, check out “pre-filter sponges” these go on the inlet of your filter and prevent gunk and debris from coating your biomedia. The water should flow through your filter in this order: Coarse Mechanical filtration (usually sponge) -> Fine mecahnical filtration (filter floss, if needed) -> biofiltration (usually ceramic rings) this prevents you from needing to clean your biofiltration as often, since all the gunk is filtered out beforehand.

These days, many “disposable filter” brands also come with ceramic rings. So if yours did, most of your beneficial bacteria will be hanging there instead of the wool stuff.

In your filter, if you have no ceramic rings, then that cotton wool like stuff will hold a good amount of your bacteria. In this case, it’s best to add your extra biomedia and leave your current filter media in their for a good month so it can spread to your biomedia.

As for how long these last. Ceramic rings and good quality sponge can last years before needing to be replace. A good sponge should be able to be cleaned with three squeezes in siphoned tank water. Lesser sponges can last about 6 months, but even then, it’s fine to swap these out since your biomedia houses your beneficial bacteria.

Purigen is chemical filtration, which is a which is separate from biological (beneficial bacteria) and mechanical (sponge) filtration. Unlike these two, it’s generally not essential. Purigen essentially “absorbs waste” before it becomes ammonia, nitrite or nitrate. It also can absorb tannins. I have a personal dislike for the stuff. Not because it doesn’t work but because beginners often use it to “hide problems” that are a result of poor maintenance (say skipping cleaning or an overstocked tank). There is a tendency to rely on purigen instead of good tank practices, which generally eliminates the need for it altogether. Not only that but the stuff smells disgusting and, although it can be reused to a point, it’s still an ongoing cost. I see purigen as an emergency solution rather than an ongoing tank addition.

Let me know if anything I have said needs clarification. I just started rambling and before I knew it, I’m at the end of my reply.

Of course, as usual I forgot to ask you something. What do you think of Purigen. . . the one that comes in a bag. Is that good to use in my filter instead of the spongy thing I mentioned?

So you’re recommending using a pre-filter sponge and ceramic rings, correct? I just looked at both of these. . . looks like the ceramic rings come in a mesh bag or loose. Which would I use? My filter is your average hang-on-the back filter. It looks to me like it’s just the white cottony thing with carbon inside (cartridge). It also has a long rectangle shaped cube, probably 4″ long with 1/2″ sides that the water falls over last. The package said it helps capture ammonia. So I should leave the old cottony filter there for about a month to spread the bacteria and add the rings and sponge, right? Then take the old one out after a month. Not sure all that will fit in there but I’ll look.

Do you think I should look at buying a better filter that will house everything I need? If so, what kind of filter would be best for my 10 gallon tank?

Thanks, Ian.

Heh, I can’t help but feel that ammonia capturing piece would have slowed down your cycle. It probably contains something like zeolite. No matter, we are past that now 🙂

I would only recommend the pre-filter sponge if there is no room inside the filter for mechanical filtration.

It doesn’t make too much difference whether you buy them loose or bagged. Loose is generally cheaper (buy a drawstring filter media bag to house them) but the end result is the same. The only difference is that with the loose, you can swap them out, half at a time (say in two years, when they eventually deteriorate) this way the bacteria in the old ceramic rings will colonize the new rings, without causing a causing a complete crash. After two weeks, swap out the other half.

I personally use Sera Siporax in my tanks, it’s essentially ceramic rings but with “more room” for bacteria to call home. I also like that they have a “mini” version which is great for HOB filters. For your tank though, it shouldn’t matter what biomedia you use, so just go with whatever is cheapest.

For a HOB, aqua clear filters hit the sweet spot in price and ability to hold everything you need. If memory serves correctly, it comes with ceramic rings too. It’s probably the cheapest solution rather than buying everything separately. Short of a pre-filter sponge, which is by no means essential, just a “nice to have” the kit should have everything you need.

The easiest way in this case to colonize the new filter is to run both HOB at the same time for 2-4 weeks, before removing the old one.


I looked online and it looks like the aqua clear filter you mentioned does have ceramic rings, as well as carbon filter insert and foam insert. But my tank doesn’t have a place to hang a second filter (cutout in the top cover). You are saying to run the new filter and the old one at the same time for a few weeks, correct? Do you know how I can do that? And so when I remove the old filter, I’d have to make sure the bacteria in the new filter is taking care of the ammonia, right? I guess I’m a bit confused as to how the bacteria will grow in the new filter any faster that it did in the old one. Am I essentially cycling the tank again with the new filter?


If you only have a single cutout, open the filter up and remove any places where beneficial bacteria could be (such as the cotton filter) and place it in the new filter on top of the ceramic rings. I’d then disassemble the old filter and leave it in the tank, just in case any beneficial bacteria is attached to the walls. Running the new filter now will have the same effect. Keep testing and keep prime on hand, just in case, you may experience an ammonia spike.

As for how it works. In a new tank there is no bacteria. When you cycle, you are not just waiting for two different types to appear, you are waiting for them to multiply. So to put it really simply, first there is 1 of the first bacteria. Then there is 2. Then there is 4. And so on. Repeat for second type of bacteria. You already have an entire colony of both in your tank right now. It takes a fraction of the time to cycle with a tank with a pre-cycled filter. If you have a good local fish store, they may even sell pre-cycled sponge filters for this very reason.

Ok. . .will do that. The only thing I’m not clear on is how to disassemble the old filter and leave it in the tank. I’ll put the old cotton filter cartridge on top of the ceramic rings and start running the new filter. But not sure exactly what you mean by leave the old filter in the tank, since there isn’t another cutout for it. Is there a way to take it apart and submerge it? Sorry if I sound stupid, I just don’t understand what you mean.

Also, the Aquaclear filter’s directions say to replace the foam every 2 months, the carbon part every 2 months, and the rings every 3 months. But I know you mentioned the ceramic rings can last 2 years. . . so are they wrong about the foam and carbon as well?


Sorry, I could have been more clear here. Simply leave the whole filter, minus the bits mentioned, submerged in your tank.

I don’t know anyone with an aquaclear filter who has swapped out their rings after 3 months. You’ll know when it’s right, they will look like they are dissolving. If and when it happens, you simply replace them with a better quality biomedia, one that will last much longer. Since your foam doesn’t house the beneficial bacteria (or as much) as your current filter, you can be a bit more aggressive in it’s cleaning. Squeezing it out in tank water until the water runs clearish will unclog it. It should last more than 2 months. Again, if it does wear down, simply replace it with better quality stuff.

Carbon is the only part they have right. Carbon is a chemical media, it absorbs tannins and bad smells among other things. Once it is “full” and can absorb no more, it needs to be thrown out or replaced. I personally don’t run carbon on any of my tanks. Unless your driftwood is drastically leeching tannins into the water, and you don’t like the look, or you are using it to remove medication after treating sick fish, carbon can generally be skipped completely.

Lol. . . sorry, but I still don’t understand. . . are you saying to take the entire old big black plastic HOB filter that is in the cutout now and has the filter cartridge and motor inside it, and submerge it? Or just some part of it?

All good, I could have been clearer here. You want to submerge as much of the section that water flows through as possible. Depending on the design, this will vary as to how simple it is to do this. The ideal however, is to run both at once.

Just had a thought, when you say cutout, is the lid removable? If so, just remove the lid for the duration and add the second HOB.

Filter parts with BB, such as cartridge, go in your new filter to seed the ceramic rings.

Sorry, I’m crazy. It was 6.0. We were messing with the tanks, water changes, ornament changes, testing, etc, all afternoon and I was stressed, frustrated, and tired. Apparently I read 0 instead of 6. . . still the lowest reading though.

What did you think about using Prime tomorrow to lower the nitrates in the big tank if another water change doesn’t work? And if so, how much?


Once your tank is cycled, I recommend that prime only really be used in an emergency, such as an ammonia spike, outside of dechlorinating water. Prime hides the problem rather than solve it. You’ll still have to eventually get rid of all this nitrate, or forever dose daily with seachem prime. I’d personally keep performing water changes, since avoiding this is just putting off the inevitable, you’ll eventually have to do them.

Yes, the lid is removable. . . I just wasn’t sure if I should do that, since I’ve heard fish can jump out. But if you say so, I’m sure it’s safe, and the babies are still probably too small to jump anyway. So having the entire top open is ok, right? I guess I could always put some kind of net or screen over it. And you said to leave the old filter running for about 3 or 4 weeks, correct?

Thanks for being so patient with all my questions!


While all fish can jump, it’s often as a result of nervousness, say being introduced to a new tank. For the short term, say cycling your second filter, removing your lid is the easiest way to go about it. If you really are concerned, or notice behavior that suggests jumping, cheese cloth or something similar is cheap and can act as a barrier.

Leave the old filter cycling for 3 or 4 weeks alongside your new one to be safe. Afterwards, remove the filter cartridge and sit it on top of your ceramic rings in the new filter. It’s a little overkill, but it’s just to be safe.

Safe sounds good to me. . . we’ve gotten them this far (with your help) and I don’t want to lose them! So I will do exactly as you suggest and run both filters for a few weeks. How often would you test the water in a cycled tank with babies?

I actually can’t think of any more questions right now, but
I have my KH test kit now and may have to ask you about that later.

Thanks so much for all your help Ian!


How often to test your water? There really isn’t a right answer, other than you can’t test too much. Once your tank has cycled, and you have your fish in. I suggest testing every day, so you can see how chemicals such as nitrate and pH change across a week in your tank (yours will be different to mine or anyone elses) Once you have a good understanding of this, you can swap over to testing with your weekly water change. You’ll have to make a judgement call to develop your own routine – as often enough as you feel comfortable to identify problems. And of course, if you think something is amiss outside of your testing routine then by all means, test!

Oh, one more thing on the filters, monitor the flow. Two filters can produce much more current than one. If it looks like there is too much water movement and it’s stressing your fish or they look like they are having trouble swimming, reduce the flow. Depending on your filter can do this by placing sponge around the intake, using a piece of plastic on the outlet so that it “flows” into the tank rather than “falls” etc. Just something to be mindful of.

When the babies were still in the 3 gallon, I was testing both tanks every day because I was worried about ammonia and niitrites harming them, and wanting to see if the 10 gallon was cycled. I’ll continue to do that until I see how things change over a week, as you say.

I did read something about how the filter current can sometimes be too strong. . .glad you mentioned that. I’ll keep an eye on it.


Hi Ian:

I don’t know if this is the right place to post this, but I thought I’d just add to this long string we already have going. I wanted to ask if I should cover the aquariums if they are exposed to bright sunlight. It’s only for a little while each day, and not every day since we get a lot of cloudy days. I read that sun can cause algae to grow, but my question is really about the fish. . . does it bother them. . . either full grown tropical fish or my babies? I’ve been covering them but didn’t know if it was necessary.

The babies are still doing well in the 10 gallon tank, as is the mother in her 3 gallon tank. I bought the AquaClear filter you suggested and will probably install it tomorrow along side the old one.

Thanks Ian

Hi Lezlee,

Your primary concern here is algae. The fish will be fine as long as you have your lighting set to a day/night cycle. An aquarium is an enclosed setting, and we want to control each variable. Direct sunlight adds an unknown to the equation. Ideally you wouldn’t want sunlight hitting your tank, but it shouldn’t harm your fish.

Happy to hear everyone in your fishy family is still doing well!

Hi Ian:

It seems I have never-ending questions!

I installed the second filter today at the lower flow speed. . . it does add movement, of course, so I put it on the end of the tank, close where the old one (on the side) is. I thought if both filters were at one end, the other end of the tank would be calmer for the babies. Does the flow from filters have to “fall” into the water, or is it ok if the water flows into the tank under or at the water level?

Also, since we have the 10 gallon cycled and things are going well, I wanted to ask about the 3 gallon again. The mother is still in it, and I’ve been testing and adding Prime every day for 11-12 weeks! I threw my calendar away but I know it was late October when I started that tank. The readings every day are still 0 nitrites and 0 nitrates, ammonia around .25, And we never skipped more than 1 day of testing so I know there were never any nitrites or nitrates. How can that be? The ammonia has at times been 2.0. Do you think I should put some quick start in it? I sure would like to get it cycled and stop having to dose it with Prime every day.

Thanks for your help!


Hi Lezlee,

For now, it doesn’t matter if it flows under water. You’ll want to adjust it once you remove the second filter, so there is some surface agitation. This impacts how much oxygen will be in the tank, and since your tank is a little overstocked, this is important.

You are going to have to remind me of the 3 gallon, does it have a filter? Is the pH at 7? What is the temp like?

Yes, it has a very small filter, and the temperature is about 77 or 78, it has a small heater too (but not adjustable). The PH was 7.6 today, and has been between 7.2-7.6 since the middle of December. It has sometimes been lower, but for the most part it has been good.

Can you you do a water change and confirm your nitrates again? As I understand, your tapwater is 5 PPM, so some level of nitrates should be showing up.

When was the last time you did a water change?

Also, ignore that this tank has been “cycling” since October. It’s more realistic to say it’s been cycling since all the parameters have been spot on.

We’ll get to the bottom of this 🙂

Hi Ian:

I was sick for a few days. . . but in the last couple of days (after 12 weeks) my 3 gallon tank looks like it’s finally starting to cycle! Nitrites at .5 and nitrates at 5. Finally! Just wanted to let you know. I’m sure I’ll be back here asking more questions sometime soon!

Thanks so much for all your help through this!

Lezlee 🙂

Hi Lezlee,

That’s fantastic news. I’m really happy to hear it. I have my fingers crossed that this is the home stretch!

Hi Ian:

One quick question. . . my 3 gallon is now reading 0 ammonia and 2 nitrites. Do you dose with Prime the same way (which would be 2 doses) if there are only nitrites and no ammonia?


Thank you Ian!!!! Yes we did a fishless cycle for the initial set up. It took about 4 weeks. We didn’t have any problems after that until the algae bloom. I guess this is a process with a huge learning curve but I have got to get rid of that mildew smell!

Hi Again,

Did you test your water parameters (ammonia, nitrites, nitrates, pH) with an aquarium test kit? This can often help narrow down the cause of problems, in this case the smell. If your test returns a reading for ammonia or nitrates, it’s possible swapping out the filters has caused your cycle to “crash” and you’ll have to try attempt a fish-in cycle if you still have fish inside your tank.

There definitely is a learning curve, but don’t worry, it gets much easier! Adding activated carbon can help get rid of the smell, but it won’t fix the cause – once the activated carbon is “full” it will have to be swapped out – it generally lasts around a month.

I’m in my second week and at the part where I am testing ammonia and nitrites daily. My nitrites are at 2.0ppm and have stayed there but my ammonia has been dropping. I added a half dose of the recommended dose (1/2 tsp because it’s a 60 gallon tank) a few days ago, and I tested it again today and it now says it’s at 0ppm. Does that mean I have to start from step 1 again? Or do I keep dosing the half doses until the ammonia starts to rise again? Thank you so much!

Hi Jon,

I’d dose with ammonia, wait half an hour, test and repeat. You want above 1 ppm in your tank so that the first beneficial bacteria that converts ammonia to nitrites doesnt starve.

I don’t think you need to start again. Just keep dosing with ammonia so that it reaches readable levels. Every time it dips below 1 ppm add more.

You should be testing ammonia daily to keep on top of this.

High, thanks for taking time to help
I have been cycling my 40 G saltwater tank for over 3 weeks now with no luck. i dosed ammonium on 20th Oct and got reading 2ppm which dropped to 1.5 and then one by 26th. on the same day i added ammonia i started to add seachum stability. from 26th Oct the level stayed the same 1 with 0 nitrite and nitrate. other tank parameters pH 8.25 – 8.35, salinity 1024, Temp 78.5. running curve 5 skimmer and some activated carbon in the sump (to control Oder)

on Nov first seeing the levels were the same, i added ammonia again this time increasing to 4ppm and increased temp to 81. from 4th Nov ammonia level is steady at 1 ppm with 0 nitrite and nitrate. i also added a boaster dose of seachum stability just after i got my 4ppm ammonia reading. other tank parameters are the same.

the last thing is that i have pink coloring over my silicon line in the sump for over 2 weeks now with very thin coat (whitish) over that is easily removed. nothing in the display T. no water changes so far.
any ideas would be appreciated

Hi Alaa,

Ammonia doesn’t disappear. It has to go somewhere. Are you sure you are doing the tests right? I only ask because I have had seen three people now incorrectly administer their nitrite and nitrate tests. This was the reason their ammonia was dropping but they were not detecting nitrite or nitrate.

thanks for reply, i thought about that so i tested 3 different samples one from main tank and one from QT, and one from my RO. i got zero from RO, .5 from QT and still one from MD. all showed zero nitrite and nitrate. i also rechecked the test kt instructions and i’m following OK. my concern is why i’m having steady ammonia level at one for over a week now without any progress.
1- restart the whole process (really don’t like it),
2-do partial water change and add fish, or
3- add another course of seachum stability

Hi Again Alaa,

Good work! It sounds like you are all over the testing, so we can narrow that down.
Are your salinity levels in order?

Seachem Stability is just going to help balance out you your tank, If you test your water and everything is A-okay, you shouldn’t need to add more. You’d want to add something like Instant Ocean Bio-Spira, which can kick-start the cycle, this is essentially the beneficial bacteria in a bottle.

I don’t think you’ll need to restart the process and I certainly wouldn’t add fish to this tank yet.

Also, is the pink algae you are seeing corraline algae?

Hi, thanks for helping
Salinity is 1024, pH 8.3, Temp 81
My main concern is why ammonia is not going down below 1 ppm if it can go from 2 and 4 to one in a few days why just keep at one after that, may be all i need is more time

Will add bacteria as advised.

Pink algae ? are not easily scrapped but the thin white film over is fragile and easily removed, and limited mainly to the silicon lines, still nothing in the main tank.

Hi Alaa,

The rate at which ammonia decreases is rarely linear. I’d stick at it for a little longer, and take daily readings to watch closely what is happening (make sure you write them down so you don’t forget them!)

HI, Bacteria seems to be disappearing

i add bacteria as advised and got my ammonia level to .5 then .25 within 36 hours, nitrite 0 but for the first time i got nitrate reading of 5 ppm, so i’m on the right track i though
i raised ammonia back to 1 on 16th ans since the it stays there with no change and with 0 nitrite and barely there nitrate
other tank parameters are still the same pH 8.3 (dropped to 8 for one day after dosing bacteria) salinity 1.024, temp 80

can’t figure out what is wrong, do i need to add bacteria daily (instructions are for weekly dose) to keep the number increasing and since there is ammonia why the bacterial colonies are not growing
i have around 35 B of dry rock in the DT, 2 marine pure blocks and some bio balls in the sump.

I’m currently cycling my 40 gallon tank. I added about 8ppm of ammonia on day 1. On day 2 the ammonia was 4 ppm, and it remained 4 ppm on days 3 and 4 also. Its not going up or going down, its just stuck at 4ppm. I know it will take a little longer to cycle because I added a little too much ammonia, but I’m getting a little worried. The ammonia isn’t moving at all. I tested for ph, and it read 7.6. I tested for nitrites, which read about between 0 and .25 ppm. Also, for reference, I have a hang on back filter with a sponge and 1 bag of ceramic filter media. (I don’t use carbon.) I have an air stone and air pump and a fine layer of bigger grained sand. It does get pretty cold, which might be the problem, but any suggestions? Thanks.

Hi Angela,

Ideal temperature range is between 65-85 degrees Fahrenheit outside of this, growth can slow or stop completely. I’d suggest grabbing a heater if you don’t have one, as temperature swings can also stress and kill fish you add, even once your tank has cycled.

Once your temperature is back on track, I’d give it a good week to see what is happening – make sure you follow the instructions in this guide!

Hi, I purchased the API Freshwater Master Kit to test my water for my fish tank. The labels said to dispose of the chemicals in a chemical facility, but on online forums, people said they are just pouring it down their sinks and diluting it. Is this safe? I’m not sure if I have time to go to a chemical facility, I don’t even know if they will take these chemicals, and it would be much easier to just pour it down the sink — but only if it is completely safe. Do you have any ideas?

Thank you so much!

Hi Amelia,

I’m not saying it’s good to dump chemicals down the drain, but the components of these test kits are things that we already dispose of via sinks and toilets. These chemicals are commonly found in toothpaste, drain cleaner and even urine.

If you were disposing of whole bottles of the stuff, yeah better to do it at a chemical facility. But if you are talking about the test tubes after testing, everyone I know washes it down the sink. As to whether it’s right or not, that’s a whole other debate.

Okay thank you so much! My older sister has had a fish tank for 3 years now, and her tiger barbs changed colors: some of them have more prominent red fins and black stripes. Is this okay?

Hi Amelia,

This is either normal or a concern. Tiger barbs will often change color when they are ready to spawn (breed). This is normal and colors will likely change back once they are over this phase.

Otherwise, color change is usually attributed to poor water quality and stress. If your water chemistry and quality are fine, then it’s possibly the first scenario.

They normally change at night, and then go back to normal during the day. We are waiting on the test strips to arrive so we can test the levels, but for now, she’s been using Seachem Prime.

Hi Amelia,

When you say normally change at night, are you saying they fade? Or do they get brighter at night? Does this happen when you switch on the light?

Also, as an aside, Id recommend a test kit over strips. Strips don’t last as long and are more expensive in the long run. Also, based on my testing and observations, they are far less accurate. Given you should be continuing to test your aquarium with your regular water change and maintenance, a test kit is an essential tool for every fish keeper.

They fade when it is darker, and I at first bought the API Freshwater Master Kit, but I really don’t feel comfortable disposing the harsh chemicals, so I’m getting the Tetra 6 in 1 strips and the Tetra Ammonia ones.

Hi Amelia,

Each to their own, these are arguably not harsh chemicals, they are everyday chemicals found in products like toothpaste, which we also put down our drains. While I commend you on not wanting to dump chemicals down the drain, these test strips also contain chemicals, but are inherently more wasteful, and they will end up in a landfill instead, where they will break down and enter the environment anyway. Damned if you do, damned if you don’t,

I’m not trying to say either way is environmentally better, just giving you some food for thought.

It’s possible your fish are fading because they are stressed from their aquarium light coming on. You can wean them into this change by turning the light on earlier (while it’s still daylight.)

Okay thank you. I might just try the strips first and go back to the other kit if it doesn’t work as well, there’s just all of these crazy warnings on the bottles, like genetic defects and stuff like that, yikes. And yes, she’s been letting the daylight light through the windows instead of the tank light to get them used to it, but they still fade at night. However, the next day, they’re back to normal. Could it maybe be hunger? She only feeds her 5 tiger barbs 2 tiny pinches in the morning, and an even smaller amount at night.

It’s quite hard to say then, without seeing the tank in person. If all her water parameters are normal, as per the tests, and fish seem normal otherwise, then it’s hard to diagnose online.

As for foods, try mixing up the diet. A combination of flakes and bloodworms (frozen or live) can sometimes improve coloration in certain fish. As for the amount of food, it sounds like thats enough food – it always surprises people just how little fish actually eat. Overfeeding is very common.

I’ve already asked a question, but I have one more, sorry that it is in all-caps, I asked another form and there format automatically put it in all caps and it’s a lot of work to change it back 🙂

Hi Amelia,

Hands down the best way to cycle a tank quickly is with a filter from another aquarium. Failing that, a generous helping of gravel from another tank can help speed things up too.

As for “bottled bacteria supplements” There are too many variables here. I know some people swear by them, but I have seen tanks cycle just as quick or quicker without the same bacteria added. It may speed up your cycle, but I’m not convinced it can consistently do so based on my own testing and observations.

As for the steps and products, I have outlined everything you need to do to cycle your tank clearly in this guide.

Unfortunately, cycling is just a process where you have to be patient. I know it’s not the answer you want, but it beats having your fish die in just a few days.

Hi, thanks for this article.
I am currently cycling my tank but I am confused about the test readings.
For ammonia, I got 0 ppm.
For nitrite, I got 80 ppm.
For nitrate, I got 160 ppm.
The test readings stayed the exact same for pretty much a week. I drained about half the tank, and filled it back up and added a dose of ammonia just to be sure there was beneficial bacteria and to try to clear this problem. Sure enough, a couple days later I tested and the readings were exactly the same as the ones above. Do you have any suggestions for this? Thanks.

Hi Angela,

Can you clarify that the max reading on the color cards are 80 and 160? If so, it’s possible that your nitrites and nitrates far exceed these levels. For example, they could be 400 or 800 and your test kit can only show the lower numbers. If this is the case, you’ll need to get these down to readable levels in order to see what is actually happening in your tank.

Hello mr. Sterling, I have a couple questions about my tank cycle. My first question is how do I permanently raise my ph? I have tried water changes which only incrementally raise ph but don’t help. I have added 1 teaspoon of baking soda which rocketed my ph to 8.4 from 6. (I have a 5.5g). My ph has dropped again to 6 and I am planning on adding more baking soda. Is baking soda safe for aquariums? I heard you shouldn’t use ph raisers found in stores . Lastly, my tank is almost cycled and I am planning on getting a betta fish. What is the best way of acclimating the betta? I have heard that you should transfer it into a plastic bag and float it adding water every ten minutes from your tank. I have also heard that you can just float it then dump it without adding any water from the tank. Should I keep the tank lights on or off during the process and if off then when should I turn them on? Thankyou!

Hi Ben,

Congrats on making it this far through the cycling process, that’s awesome and will make things easier for you in the future 🙂 Make sure you keep an eye on the pH, low pH levels can halt your cycle. I’d hate to see you go backwards this far along, so it’s something you need to get on top of.

The reason pH raisers are dangerous because beginners use them without understanding the relationship pH has with KH, leading to the pH bouncing around and killing their fish. It sounds to me like you should measure your KH, it has a direct impact on your pH, I have a guide on KH here I know it can seem like a lot to take in at first, but don’t worry, this gets easier!

I highly recommend drip acclimatization. There are plenty of guides on this online – it will give your fish the greatest chances of survival. Depending on many other factors, a 10 minute float can shock your fish, same with adding your fish directly to your tank. These are not a good way to start your fish keeping journey, even if everything looks fine, it might stress your fish out to the point that it dies a few days later.

As for the lights, it’s less of an issue if your fish is being brought home in a clear bag, from your local fish store. If you order your betta online, it will arrive in a dark box – the bright lights here can certainly shock your fish.

Hi Ian,
We’re new to fish keeping and have been trying to cycle a 5 gallon tank for just under 2 months (starting 10/6). Ammonia just started to drop to zero in less than 24 hours 11/17, but nitrites continue to be off the charts. I add enough ammonia to get a 1.0 ppm reading every day.

After reading through your comments I saw someone had success figuring out nitrites with water changes, so I have done 3. The 2nd did get nitrites down to readable levels (2 ppm, which I figured out by doing half tap water and half tank water since 2 ppm and 5 ppm on the test are so similar). But the next day nitrites were 5+ again. We have well water, ph in the tank is 7.6, temp is 71.
I am using the API Freshwater test kit and have tested our well water, which shows 0.25 ppm Ammonia, 0 nitrites, and 5 ppm Nitrates.

We’re trying to be patient but we’re coming up on the 2 month mark and we do have a betta fish (in a 1 gallon heated bowl) that we want to move into the 5 gallon. We didn’t do a fish-in cycle after reading about it and because he’s dealing with fin rot so we didn’t want to put him through the bacteria spikes. We do frequent water changes in his bowl.

What do you suggest? I appreciate any advice or insight you can provide. Thank you for your whole blog and answering comments!

Hi Brittany,

Well water can certainly make things interesting when cycling as it can have a whole bunch of other things dissolved in it that test kits won’t pick up. I’m not saying that this is the reason for the slower cycle, but it is possible.

I can completely understand your frustration given you have a fish waiting to make the transition but given the bout of fin rot, I applaud you for not attempting a fish-in cycle with a sick betta – I wouldn’t have liked it’s chances of survival.

With that said, everything sounds normal, although it’s possible you are having problems with the second bacteria forming slower than expected – the nitrite eating bacteria.

The big question question I have for you is, what are your nitrates doing? Are they slowly growing in number on a day by day basis? Or are they halted at 5ppm? (the nitrate of your well water) You may need to keep checking for the next few days to confirm what it is actually doing. As the nitrate production increases, the nitrite growth rate will decrease. If you measure these side by side you may get a better idea of what is happening?

Also, and I have no doubt that you are already all over this given your attention to detail so far, but don’t forget to raise the temperature of the tank once it’s cycled, betta love that warm water.

Nitrates really haven’t shown progress at all, still 5 ppm. I have been testing in hopes of seeing change at that end to worry less about the nitrites still being 5+. Do you think we should just continue to test and wait it out, or is there anything else we can do?

Thanks for the reminder about the temp. We’ll transition the heater over to the 5 gallon once it’s cycled. I was researching to confirm that the bacteria should be okay with the temperature increase. Do you think it will be okay? Additionally, the bio load from one fish should be able to sustain the cycle once it completes, is that correct?

Thanks again!

Were I in your situation, I’d give it another week before I started looking for solutions, continuing to do water changes to get the nitrites down to readable levels, so you can see what’s happening (whether they increase at the same rate or the increase is starting to slow). Unfortunately, the first step of fishkeeping is the most boring and much of it is just waiting around for something to happen.

If the week passes and you see no results, I would consider trying a bottled bacteria supplement, although you could attempt this now if you so choose, it won’t slow down your cycle further. Just be mindful that if you live some place cold then the bottled bacteria could be dead before it reaches you, say due to poor transport or storage – it’s a bottle of living organisms and they don’t handle extremes in temperature well. Unfortunately, there is no way to tell if the bacteria you are adding to your tank is already dead. Throw in the fact that different brands offer different strains and you have my reasons for generally avoiding it. With that said, I won’t deny that some people do see success with it during an otherwise slow cycle.

As a side note, do you know any other local fishkeepers on the same well water as you? How did they find the cycling process? Asking around could also shed insight into why your cycle is taking so long.

The temperature increase should not impact the beneficial bacteria at all. The temperature you would keep your betta at falls well within the habitable zone of the beneficial bacteria.

You are spot on regarding bioload. We generally try to “build” more beneficial bacteria than is needed during the cycling process. Once the fish is introduced, the bacteria “dies back” to a level that can be supported by the waste of your fish – since there are only so much ammonia and nitrite that can be fed upon.

Hi Ian,
Just wanted to follow up after all of your help before. I ended up waiting the week and then buying Tetra Safestart+. I was lucky and that helped; the tank started cycling ammonia and nitrites and I was able to get my Betta in after another week. So far so good. I’ve done weekly 25% water changes and will continue to monitor the water. It’s been a little harder to tell between 0 and 0.25 ppm ammonia on the test since my fish has been in the tank, but I’ll keep tracking to see the pattern.

To address your side note, I found one other family with a tank in my town but it ended up not being much help as they don’t test their water (so I guess they did an fish-in cycle). Additionally, the local fish store is on city water and just said to use the instant cycle products.

Thank you so much for all of your help!!
Kind regards,

Hi Brittany,

That’s fantastic, I’m really happy to hear you found success! TO help with your ammonia, when it’s zero, it’s perfectly yellow. When it’s 0.25, it has a slight green tint. You’ll see this best if you look at the test outside, in natural light. The lights on your ceiling can make the two look a very similar color. Here is an example of the colors you should. Just make sure night mode is off on your phone, so that it’s a true representation.

Oh wow, I’m sorry to hear about your difficulties in finding fishkeepers on the same water as you. That would have been frustrating. At least your cycling journey is over and you’ll have cut out many problems that people who skip cycling face.

That’s what I thought. While I was waiting for you to answer, we went ahead and did a second 50% water change. . .so we’ve done 2 changes today. I didn’t know what else would lower the nitrates. They still read at 40-50, it’s hard to tell the exact red. I read that Prime helps. . . is that something I should try tomorrow if another water change doesn’t lower them enough? Because Prime doesn’t remove the ammonia, just makes it safe for the fish and still leaves it for the bacteria, correct? And what level of nitrates would you consider safe?

We were all ready to move the babies. . . had everything ready and then the nitrate problem! So frustrating! I was looking forward to having only 2 tanks. Oh, well, hopefully tomorrow.

Thanks again, Ian.

Prime won’t lower your nitrates, just “bind them” temporarily. Ideally you want them out. It’s no biggy. Just keep doing water changes as you get them down. In a perfect world, you’d ideally want them under 10. Lower is always better unless you have a planted tank. I go off 40 as the max upper limit for freshwater fish. However that’s not to say that 40 is acceptable, rather it’s the stage I’d panic and do an immediate water change kinda thing.

It’s likely this nitrate has been left to build up as you have constantly been adding ammonia to keep the bacteria alive and this is the end result.

While doing extra water changes is a pain in the butt, it won’t harm your tank. You are nearly there!

Thank you for this information!! My wife and I are cycling a 29 gallon planted (soon to be) tank, and I am not sure where to go form here. My readings are:

ammonia about 1ppm
Nitrite about 1ppm
nitrates about about 40 ppm.. hard to tell the color

The water from my tap is:

ammonia .25
nitrite 0
nitrate 20

should I keep putting ish food in there to decay, or should I let it go, and see if ammonia and nitrites start to go down a bit?

thanks again


Hi Greg,

You can substitute the recommended ammonia for fish food, although I recommend ammonia because it’s measurable. The instructions make it clear that you want to continue giving the first beneficial bacteria food (ammonia) through the cycle. Your problem is that fish food is going to consistently give off ammonia as it decays however, if your ammonia is staying constant at 1 ppm, then you still have a fair way to go in the cycle. If your nitrates exceed the color card, use a water change (or three) to bring it back to measurable levels – so you can see what is happening.

I think I’ll vacuum it out tonight, and start with some ammonia powder. I am doing a 25% water change in my 60 gallon tonight as well.. So i can use that water, and borrow one of the filters from it. Patience is not a strong suit of mine 🙁

If you can borrow a pre-cycled filter, you’ll dramatically speed up the cycle. Water on the other hand won’t help too much – the beneficial bacteria isn’t free-floating. It clings to surfaces. You’d be better off adding a cup of gravel to go with it. Yeah, this first step definitely requires patience, especially when you have your eye on some fancy new fish you want to add. But it will be worth it in the end!

Hi. Thanks for all the info. I am in my second week of cycling a 55 gallon freshwater tank. When cycling is done, what maintenance if any do I perform before adding fish? Water change, charcoal change, filter change or cleaning? I have a Cascade 1000. Thanks

Hi Chris,

Good question,

You’ll certainly want to do a waterchange (or three) to get the nitrates back down to acceptable levels. This is probably the most important part.

Otherwise, everything else is pretty much optional, such as wiping down the glass of your tank (if any gunk has started to appear) etc. If you were using pure ammonia, your mechanical filtration likely doens’t need cleaning yet, charcoal is there to remove either bad smells or tannins among other things unless you have problems with those, it’s an optional extra, You’ll know when that needs replacing because either the smell or tannins will return. A quick examine of your tank once cycling is done will clue you in to any changes you will need to make. If you are unsure, I am happy to clarify.

Hi there!
I would like to ask a question about this topic. I started cycling 2/01/2019 and it’s been 11 days since I started. I constantly test my water parameters and my ammonia levels are about 2-3ppm but I don’t get any rise of nitrite levels in my test kit. I am kinda worried about this and I don’t know what to do, so if you could give some advice, that would be lovely.

– Hans Jeremy

Hi Hans,

Just some follow up questions, so I can better help you:

1. What is your pH?
2. Are you dosing with ammonia regularly or has it been 2-3 since you started and you havn’t added extra?
3. Have you tested your nitrAtes if not, what do they read?
4. Have you followed the instructions to the letter on your nitrite test kit (shaking etc.)
5. What is the temperature of your aquarium.
6. Is your filter set up with biomedia?

Are yoHave you tested your nitrate levels? In very few instances,

Hello there once again,

I feel like I’m doing the wrong thing because I only have my filter running in my new tank since 02/02/2019. I’ve been putting fish food in my tank and waiting for it to decompose as it says in wikihow website. Yes, I tested the Ph, Ammonia, and Nitirites. The readings are Ph:7.6 (dark blue), Ammonia: between 2-4ppm (kinda hard to read), Nitrites: 0ppm (light blue). I’m starting to wonder if I’ve been doing this whole cycling thing the wrong way. Should I start all over again?

Hi Hans,

That wikihow article reads as though it is written by someone who has never kept fish, instead just copying information they found online. The instructions are vague to the point of being dangerous “perform a 50% water change” for instance may not get your nitrate levels down to a level safe for fish. If you are following their method, you should direct your questions there. Any advice I give relates to following this guide.

I personally only use liquid ammonia, as per my guide. It’s only been a week, so no need to panic just yet.

Also, you did not answer all my questions. I cannot properly advise if you do not answer all the questions.

I now have an additional question, are you using a water conditioner?

1. Ph:7.6 (dark blue) I took this today
2. I am not using the pure liquid ammonia, I’m using fish food.
3. Yes I tested my nitrites today and it’s still at 0ppm
4. Yes I followed the instructions in the API Master Kit manual
5. That is the problem I forgot to buy a thermometer for my Aquarium
6. Yes my HOB has a biological media
and I used stress coat water conditioner.

It’s just been one week and two days since the cycling started. Gee where are my maths. Sorry about that.

Hi Hans,

3. Is asking for your nitrAte level, not nitrIte. What does it read?

As long as your temp is above 65˚F, ideally over 75˚F will cause Beneficial bacteria to appear quicker, I highly suggest buying a thermometer so you can keep track of this, it will help you troubleshoot when your have fish inside your tank too.

You can grab a bottle of tetra safe start if you are having trouble, and giving it another week, testing daily.

I did a water change 6 days ago when I moved the babies out of that tank. . . and the mother back into it. I’ll do another tomorrow and let you know the nitrate readings. I’ve never tested my tapwater for nitrates but I’ll do that tomorrow too.

Thanks again.
Lezlee 🙂

I’d do a 50% water change or two and add tetra safe start. There may be some problems with the initial beneficial bacteria appearing for whatever reason, this may help boost it.

I appreciate the step by step guide with specific product examples. This is one of the best guides I’ve seen.

I did have some questions about your chart. Shouldn’t your ammonia chart start around 4 ppm rather than slowly ramp up? Shouldn’t you keep it below 5 ppm? And once it starts dropping, shouldn’t it show how you added more to keep it from going to 0?


Hi Gray,

Excellent question – you are spot on. This is actually a chart from a fish-in cycle. I couldn’t find my notes on my last fishless cycle. I added this as an example as to how the different chemicals move over time. I am sorry if this added any confusion, I honestly thought this would be a good example to show. But I love feedback, do you think it should be removed?

I have been following your instructions for a fishless cycle on a 44 gallon tank in setting up for Discus. Thought I was there last nite.
Temp 83.7
PH 7.4
Ammonia 0 ppm
Nitrite 0 pm
Nitrate 40 ppm
KH 107.4 ppm

Redosed with ammonia at original amount. Tested 24 hrs later
Temp 83.7
PH 7.4
Ammonia 0.25 ppm
Nitrite 1.0 ppm
Nitrate 80 ppm
KH 89.5 ppm

What should I do? Water change? Add more ammonia (full or half dose?) and hope in 24 hours it and nitrites drop again to 0???

Also when I do get 0 readings again and they stay for a few days, how do I maintain my cycle? When I confirm cycled it will take 7-8 days to receive my fish. Thank you!!

Hi Kay,

That all sounds positive. I’d keep adding ammonia and check again in a few more days – it needs to be zero within a 24 hour period. It sounds like you are almost there!

As for when you get your fish, dose daily with ammonia. You want to be able to maintain the ability for it to turn your dose of ammonia to zero each day until your fish are inside the tank.

Thanks Ian. I’ll do a half dose of ammonia again tonight and recheck tomorrow. Is it normal for ammonia to be zero and nitrites zero 24 hours after adding a half dose of ammonia and then to jump 24 hours after a full dose of ammonia? How many days of returning to zero do I have to have before I add another FULL dose of ammonia? And do I have to add a full dose of ammonia? Or can i just continue with half doses (confirming zero ammonia and nitrites) until fish arrive?

Also you say to do a partial water change after tank cycles, since I’m not adding fish right away do I do a partial water change after I confirm tank is cycled or wait until I’m ready to add my fish?

Thank you for your help.

Unfortunately there isn’t really such a thing as “normal” Due to the sheer number of setups, everyone experiences the cycle slightly differently. But based on what you are saying, I don’t see any cause for concern yet. If after another week the same is happening,then it’s time to investigate.

At this stage you should continue to add a full dose of ammonia once it hits zero and continue to do this until your tank is cycled and your fish arrive.

As for the partial water change, it entirely depends on your nitrates. I like to keep them on the low end as it allows me to determine the rate at which nitrite is converted to nitrate (as you may have noticed, your card has an upper limit after which it can no longer detect higher levels of nitrate) the excess levels don’t matter until you add fish though. So you can wait if you want.

Please let me know if any of this needs clarification. I’m on my phone and my thoughts are a little disjointed.

Will do. Thanks!

Oh by the way. I just reran all my tests again four hours after the last one. I didn’t add any ammonia or change anything. My parameters are now

PH 7.2
Ammonia 0 ppm
Nitrites are back to 0 ppm
Nitrates 80 ppm
KH 89.5 ppm

Will add full dose ammonia and retest in 24 hours.

Is it possible for things to change that quick? I’m sure I tested correctly before.

Thanks again. Will keep you posted.

Yeah it all happens quick towards the end of the cycle. This is really promising and should reassure you that you are almost there. Just keep adding a full dose daily and it won’t be much longer now.

Hi again Ian. Ok my tank is cycled! Time for my water change. How much of a water change should I do? Remember I don’t have my fish yet so I do t gave to worry about stressing them. Thanks.

Hi Kay,

That’s awesome that you reached the end. Well done! Since you have no fish in your tanks, I’d aim to get your nitrates down under 20. 10 is ideal. I suggest doing daily water changes of 50%. This will roughly halve your nitrate levels each water change. Depending on how high your levels got, this could be a few water changes. Don’t forget to dechlorinate the new water beforee adding it. Also keep adding that ammonia. 🙂

Hi again Ian. I’m having a bit of a problem with my newly cycled tank. I’ve done a water change everyday. Last water change was 50%. Brought my nitrate level down to 20. Level is back up to 80 again today. Can’t seen to lower it and have it stay down. I even did a water change of around 80% two days ago. Nitrates keep bouncing up to 80. Any suggestions? I’m dosing daily with ammonia as I don’t have fish yet. Ammonia and nitrite levels are consistent with my additions. PH has increased to 7.6 from 6.0when tank was first cycled. I’m going to have discus so a low PH was preferable any suggestions how to lower nitrates and keep them down. I have a 44 gallon tank with an Eheim Professionel 4+350 canister filter and a Hydor inline heater.

Hi Kay, is there anything else in your tank that could be breaking down and producing ammonia? If you suspect this is the case, give your tank a general clean.

According to Salifert 1 ppm ammonia –> 2.7 ppm nitrite –> 3.6 ppm nitrate.
So if you are dosing correctly, it shouldn’t be spiking back to 80 from 20 in a single day.

I’ve been dosing with ammonia daily. 24 hours later ammonia and nitrites are both at zero. So I dose again and in 24 hours both are zero again. I have 4 small sword plants and a couple small java ferns tied to a piece of Malaysian driftwood. Fluorite substrate with a layer of spectrastone gravel over it. Take water looks extremely clear and polished. I’m also running two air stones at a moderate flow.

Hi Kay,

Nothing really stands out there, unless your driftwood or ferns are rotting. Are you reading your tests outside in natural light. The day after a 50% water change bring nitrate down to 20, it shouldn’t be hitting 80. Not unstocked. If I was in your position, I’d get the nitrates down to 5 or even 10 and then record hourly, to see the rate of increase. The next step, unfortunately, is trial and error, removing things from your tank one at a time until you find the cause.

Just reran the nitrate year again. It’s at 80. And btw my tap water has these values
PH 7.4
Ammonia 0
Nitrite 0
Nitrate 0
KH 196.9
GH 53.7

Hi again Ian. I’m not sure but I might have found my problem but don’t know how to solve it.tge inside of my canister filter tubing is coated with some sort of algae or slime. Cannit tel what color it even is because tubing is black. Popped tubing from canister and tried to rinse it but it’s inpossible with the inline heater and the attachment for the canister. I cannot remove these things since they are really stuck on. Should not maybe use some type of additive to lower (or control) nitrates thus lowering algae?

Can you swap the tubing out completely? Additives will lock you in to using them for life and won’t really help with your nitrate issues.

In my area I would have trouble finding replacement tubing and I really don’t think I can get it off without ruining the inline heater and the connector for my canister. Very frustrating considering everything is brand new and not cheap. Could this be why my nitrate numbers keep bouncing back up? It’s strange though cause I haven’t had any jumps in ammonia levels OR nitrite. What would happen if I ran tank a day or so with zero ammonia and zero nitrite?

Hi Kay,

If you cut back on ammonia, the beneficial bacteria will die off. How quick this happens depends on a variety of different factors. The ideal is not to do it. As per my previous post, I’d retest hourly before using the process of elimination and using the results here to take action.

Hi again Ian. One quick thought. Can Discus Buffer which is phosphate based contribute to high nitrate levels? Thanks!

Hi Kay,

To the best of my knowledge, Phosphate as an additive does not have a correlation to nitrate spikes. If you are currently using it, you can discontinue it through your elimination process.

M. Sterling ,

I have been following your guide in order to cycle my 10 gallon tank. I began cycling the tank on Dec 30, and everything seemed to be going as you mentioned until this week. Currently my levels are as such Temp 68 degrees , Ph levels 7-4 – 7-6, Ammonia 0 ppm , Nitrates 5 ppm ( water turns purple immediately ,) Nitrate between 10 – 20 ppm . I went ahead and did an 80% water change but the nitrites were still off the charts . What should I do , should I do another water change or just ride out the nitrite spike ?

Hi Liz,

I’m confused, what are your nitrite levels? A nitrite spike is normal, but if it’s outside your testing range, another water change won’t hurt. Just make sure you are using your test kit as per the instructions and reading it outside in natural light – orange lighting can throw off your results.

I am using the API freshwater master kit and the highest nitrite readable level is 5.0 ppm . I have been reading them in natural light I was just worried since the levels didn’t drop after such a large water change. I apologise it seems I typed nitrates instead of nitrites in my previous message .

Oh, I understand what you are saying now. No need to apologize, I have made the same mistake a million times now.

Because the card only goes up to 5ppm, it’s possible your nitrites exceeded 20 ppm. An 80% water change here would still put the nitrite in the water at 5ppm or higher. Try another 50% water change and see if you notice a difference?

Mr. Sterling,
I added ammonia to my aquarium over 2 weeks ago. I conditioned my water and I have all my electronic components hooked up. As far as I can see everything is in perfect order, however, my ammonia levels haven’t budged. Nitrite levels remain at a hard zero.
PH 7.8
Ammonia 2ppm
Nitrite 0ppm
Temperature is 78 degrees F

What could be wrong?

Hi Alan,

Have you made sure you are following the test kit instructions to the letter? It’s possible to make mistakes here and I just want to cross the obvious off the list.

You should be checking your reading outside in natural day light – the glow from indoor lighting can can make your test look off-color.

Next, have you tested your nitrate levels, just to see what is happening here?

It’s highly unusual for a cycle for stall for 2 weeks given your testing.

Ok, I was actually misreading my ammonia levels due to indoor lighting, they were much higher than I thought. I did a water change to bring it down to about 2ppm. Almost immediately I started getting a positive reading for nitrites. Soon my ammonia was dropping fast enough that I had to add more every day, then all of a sudden, it stalled. After a few days I realized I needed to check my ph and sure enough it was at a low 6.4. Another water change fixed this but now neither my ammonia nor my nitrites are dropping. Maybe the ammonia is very slowly but it’s difficult to tell. Did my cycle start all over because of the period of low ph?

6.4 is low, but it shouldn’t be low enough to cause a cycle to stall. Is there any other change you have made in this period? A sure fire way to test this would be to raise the pH (you can google the Sodium bicarbonate method) and if the cycle resumes, then that could have been the issue. Unfortunately, a lot of fish keeping is experimenting and finding what works for you.

Before I found a pure Ammonia source, we have been using Fish Food.

Water is 80 degrees, ph 8.0, Ammonia 4 ppm, Nitrite 0.25, Nitrate 0

Should I continue the fish food cycling or switch to Ammonia? Do you use any water conditioners/treatments during cycling?

Hi Jim,

I don’t do the prawn/fish food method because you can’t dose a specific amount of ammonia. It’s much easier to identify what is happening in your tank through testing.

That’s not to say you can’t do it this way. This is just my preferred method, allowing me to easily troubleshoot. Since nitrites have appeared, your cycle is well underway. In your case, I would continue doing what you are now, since you are comfortable with it.

In a fishless cycle, the only thing you need is dechlorinator. Things like API quick start may help speed up your cycle, but there is no guarantee.


I received my Master Kit today and just ran my first test. I decided to test all my parameters since the tank has been running with all electronics on for almost a week. I have two Anubius in my tank with no fish. I tested my tank and here are my results:

Ammonia: 2 ppm
Nitrite: .25 ppm
Nitrate: 20 ppm

I am kind of stuck and not sure what to do next. I have just ordered the ammonia chloride(amazon) but it won’t be in my hands for at least a week. What do you think is the best next step?

Thank you very much!

Hi Brandon,

It looks like your tank is cycling already. Those are all positive measurements. Keep testing each day and see what direction each is moving in. You’ll need a few days of data here before you can make a judgement call but based on this, there is nothing to worry about.

The only thing I would double check is your tap water, sometimes these chemicals are found in your tap water and can skew your readings. It’s always good to know what is in your tap water anyway!

Thank you for your quick reply!

I just checked through the county reports and did indeed find that in the water quality report that there are the following:

Fluoride: .8 ppm
Nitrate(as Nitrogen): .8 ppm
Chlorine(Free): 1.62 ppm
Chlorine(Total):1.71 ppm
Total Trihalomethanes(THMs): 38 ppb
Total Haloacetic Acids(HAA5): 9 ppb

I am currently using an Aquavitro alpha for reefs water conditioner. Do you think that is sufficient enough to condition my tap water for my tank or do you think I should purchase a different water conditioner? And also I believe my tap water could explain why I have some amounts of Nitrate. Is there anything I should watch out for?

Thank you again

I believe that water conditioner should work fine, however you are likely over paying for it (Aquavitro is Seachems overpriced in-store only brand) A bottle of Seachem Prime for your tank would be more than sufficient, I find it to be cheapest off amazon, so if your current conditioner runs low, order ahead. At the end of the day, both will work fine.

Again, everything seems about what you would expect. I’d work towards maintaining your 2ppm of ammonia and monitoring what your nitrites and nitrates do. Depending on where you are at in the cycle, I would expect nitrites to go up before dropping down to 0 while your nitrates rise continuously. If your nitrates get to the higher end of the chart, a water change will dilute them to measurable levels. Just make sure you re-dose with ammonia as this will also be diluted.

Hi my names Tim I’ve lost 6 arowanas in the past week Advice I love thirst fish and are tired of digging holes for them please help

Hi I am cycling my new aquarium and I believe everything is on the right track, after a week, however something changed in my tap water and the pH went down from my tap which of course I have been putting in my tank. I have live plants in the tank, upon which a pond snail has been found and I don’t mind that he is there but he seems lethargic and I was wondering if the pH level dropping might have affected him and wondering what I should do?

Initial pH with tank set up from tap was 7.2
After checking the pH yesterday in the tank and from the tap it is now 6.4

ammonia levels are 2ppm
nitrites levels are 0.25 ppm

Should I add a pH buffer or just keep checking it and doing water changes? Should I remove the snail in an effort to make him healthy again or let him ride it out as well?

Thanks for the help, great website by the way

Hi Kerry,

If your pond snail is lethargic, it’s either the ammonia or the fluctuating pH. The pH is the bigger concern here because pH under 7 slows down the appearance of beneficial bacteria. I’d keep an eye on the pH and only use a buffer if needed. If the tap water is continually 6.4 then adjusting it upwards can help speed up the process. Although if the fish you plan on keeping tolerate 6.4 then it shouldn’t be a big issue either way. As for the pond snail, 2 ppm of ammonia is quite high. I don’t really have a solution here since keeping him alive would require you to switch to a fish-in cycle. And even then there is no guarantee the snail will it through.

Hello Ian, I have a couple questions. I recently purchased(from a friend) a tank already set up. we had to remove 75% water for transport. I left all the gravel and ornaments and same filter in. How long before I should change filter(they had 3 extra filters for me) and is there any special way of doing this? Also, I just bought a brand new 36 gal bow front tank for my bedroom. Do you recommend that I used the filter from the already established tank to help with the cycling. and if so, how much time would this normally cut off the cycling process?

Hi James,

These disposable filters are a bit of a scam. When you throw away the filter, you are also throwing away the beneficial bacteria that hides inside. If you don’t have any other biomedia, like ceramic rings, then you can crash the cycle resulting in all kinds of problems. I recommend buying a filter that allows you to install both mechanical (sponge) and biomedia, so if you dispose of the sponge, it won’t cause you any issues.

If the filter dried out, the it’s possible the bacteria have died. As for how much time it will cut off? It depends. It could reduce the cycle by a day, it could reduce it by weeks. There isn’t really a way to measure this.

thank you so much for your quick reply. im new to the hobby so the only thing I know about filtration is the filters they sell. lol I have a 36 gal bow front setup and I got a marineland penguin 350 on it. I wanted a little more gph than standard. another question I cam across, I am on day 3 of the cycle(using your guide). my ammonia level is between 2-3ppm and my ph level is 7.6. my tank seems to becoming a bit cloudy. is this normal or should I do a water change? if water change, how much water should I change? I am thinking between 25-50% but what do I know? im a beginner. lol btw, thank you for your time on answering these questions to people. this world needs more people like you willing to help new and upcoming hobbyist.

My pleasure, James.

The cloudiness is actually a bacterial bloom. These often appear during the cycling process and go away on their own. Like the beneficial bacteria, these bacteria are harmless. If they have appeared, you may find that your tank will get cloudier and cloudier until one day it reverses, and get’s less and less cloudy. Generally, the cloudiness clears up once the nitrites start appearing.

The only time you will need to do a water change during a fishless cycle is if either ammonia, nitrite or nitrate exceeds that of your test kit color chart. For example, if your nitrate is 300 PPM, you would never know this because the test kit only goes up to 160 ppm. You can use water changes to reduce the amount, to get it back down to readable levels.

Hi there. I am just in my first week of trying to do a fishless cycle for the first time. Just wondering if you could help me with a few questions…
Should I be doing water changes, using a grave vac, or cleaning of any sort while cycling? If so, how often?
I am using the fish food method to get things started. The tank is starting to stink. Is this normal?
Is there a ph level that is too high while cycling? Ex, mine is 8 at the moment.
I have a fairly small, basic filter that just has removable cartridges, and some sort blue plastic insert. It says to change the filter every month. So, am I just losing all my good bacteria then? Or does the bacteria live in all parts of the fllter?… Gosh, this doesn’t make much sense, does it…
Anyways, thanks.

Hi Sara,

Depending on the fish food, yeah, this can be expected. I dislike using fish food for the reason that you are not adding a specific amount of ammonia to your tank. It can make the cycle less expected, but you’ll get there the same.

If you are using fish food, you might need to clean. If you are using ammonia as per my method, there isn’t really a need to. The only time you would do a water change is to balance ammonia, nitrite or nitrate levels, if they seem exceedingly high, out of the range of your test kit.

A pH of 8 would be on the high end, but you should still be able to complete a cycle here. If it goes higher, there may be cause for concern.

I’d suggest moving to a filter that has room for biomedia, like ceramic rings. These are a home for your beneficial bacteria. Disposable filter cartridges are a newbie trap, if you throw them away you throw away your beneficial bacteria. They are one of the worst things to happen to fishkeeping.

Hello Mr. Sterling. I have taken everything out of my tank and so far my ph hasn’t dropped. There are still enough bacteria to eat 4ppm of ammonia in 24 hours. I went to the pet store and got silk plants and more gravel. I washed the plants and gravel throughougly without using soap. I just added all of they new things into my 5g tank. Is this bad? Should I have done anything different. Hopefully I won’t get another ph drop. Thanks! -Ben

Hi Ben,

That sounds really positive. If you added things cause a pH drop, you might have to trash them completely. But it sounds like you are on top of everything, which is awesome!

Ok sounds good! My nitrates right now have spiked to 80ppm. Should I do a water change? Will high nitrates affect my tank at all without a fish? I am waiting to see if the new decorations will cause any change in my waters ph before I get a fish.

Nitrates should be kept as low as possible, ideally under 40, but 10 or under is fantastic. While they are not toxic, this is only true while they remain at low levels. I’d do a couple of water changes to get this down before adding a fish. Good call on waiting, the last thing you want is to experience pH swings while a fish is inside!

Hello Ian,

Thank you for your article and your very well constructed blog!

I am a new fish owner and completely new to the hobby. I recently bought a blue and red delta-tail male Betta for my soon to be 6yr old as a first pet. Needless to say I fell into many traps. I have since done more reading on proper fish care over the last few weeks then I ever thought I would do in a life time.

Bottom line is I got attached to the little guy, his name is Delta after his tail type and the fact that his coloration matches the Delta airlines tail (extra aside – my son love to fly on Delta and wants to be a pilot), and want to make a proper tank environment for him. For now, he lives in a 1.5 gal with no heater or filter. I do partial water changes every 2-3 days and test his water for ammonia levels every day.

Since bringing Delta home, I have already bought a 5 gal with a quiet flow 3 gal filter and a 100 watt adjustable heater, digital therm, 5lb gravel, Argentine Sword, Narrow Java Fern, Anubis Petit, assorted dormant plant bulbs, Asian lantern decor, a soft foam lily pad hammock, and countless other things needed. As you can see a lot of time effort and money is invested in getting things right…

I am on day 10 of my fishless cycle and no sign of nitrites or nitrates… like I said I fell into many traps, along with getting most things right eventually. I bought a bottle of Dr. Tim’s bacteria. I tried following the directions, but the bottle says add fish immediately. I did not, I bought ammonium chloride as well and dosed the tank as if a fish was in the tank. After 7 days of this and no sign of nitrites I rebooted the tank. My first attempt just had gravel, filter and heater and the filter was one of the ones that you call noob traps (indeed). But for 12 it is a great filter for Betta’s it has very low flow and is so quiet I cannot even tell its running. I am going to put ceramic rings in the very small open space it has but for now I have a bunch of cut to size floss in it to create lots of surface area for bacteria. I don’t think I will ever buy the filter cartridges I will just make my own, like you said you are asking for your tank to crash when you throw your spent filter out.

So, on to my next mistake. After the reboot I added the plants to the setup. All the plants are thriving and 3 out of 9 bulbs have almost out-grown the established plants that I added. During this reboot I found out on day 7 that my ammonia was off the chart. I finally found a reliable way to read my tests. I was having all kinds of trouble trying to match the colors as the test tubes bend light so much. I can say that now since day seven my ammonia has been higher than 1.0 and less than 4.0 I would say 2.0 steady.

I would say I am on day 4 after regulating the ammonia my ph is 7.4 and the temp 74 F. I still have no nitrite reading. My filter media has a healthy green brown glow (not bright white any longer) and there is a light opaque fuzz like coating some of my plants leaves, as well as a thin clear film on the top of my water. IS THIS OK? Should I stay the course?

My plants are thriving and my test reading seem like they are all were they should be if I were just starting a new cycle. Do you have any advice, concerns or questions? I just want to do this right and have never had the experience before.

Delta’s Dad

Hi CJ (Delta’s Dad)

That’s a pretty funky name for a fish. I love that you can relate it back to your son too!

I’m terribly sorry to hear about your experience so far. Trust me, it get’s so much easier from here on out. Hang in there! The good news is that you have already identified and fixed just about every error you have made. You should be proud of your research efforts here, you have done a great job.

On the tests, if you read them outside in natural daylight, you’ll get a much more accurate result. Indoor lighting can often return an incorrect reading, especially under yellow/orange lights. If you take the tests outside in the middle of the day it will be much easier to identify the color.

The light opaque coating on is perfectly normal on your newly added plants. It often appears on new plants or even driftwood and disappears on it’s own. Some people call this a “biofilm” others call it a white fuzz or transparent film. It shouldn’t be a cause for concern, unless it’s still hanging around after a month.

The thin clear film on top of the water could be cause for concern. As to exactly what it is, This article will help identify and fix it but the short answer is that surface agitation (say from a bubbler or the outflow of your filter) should break it up. You’ll want it gone, it reduces the amount of oxygen that can enter your water. Since the beneficial bacteria are aerobic, it’s possible that reduced levels of oxygen could slow down the cycle.

But besides that, based on what you have written, nothing seems out of the ordinary. You just have some more waiting to do, as nitrites appear within the first two weeks.

Let me know if I can be of further assistance at all!

Thank you Ian,
You are a true gentleman. I have read a lot of your blog already and you are always speedy to respond and always offer an encouraging word even when some others come here seemingly just to refute your experiences…

Thank you!

Yes, the lighting was the issue for testing I actually change the bulb above the tank to white light and read all tests in the same place next to the window.

So, I was thinking that the film may be limiting my oxygen levels. This makes sense. The film does not cover the complete surface of the water and the filter does break it up a little. I will use a paper towel and fish net to clear it up and I will try to reposition my filter to get more agitation out of it. Is there a way to test oxygen levels in my water? Thank you for the additional reading.

As for the cause of the film, I cannot be sure but it could be my hand or the pump. But, I am also thinking that from time to time I light a candle on the same table and the residual burn off might be settling on the water??? There is no fish or reason for food in the tank.

I was thinking about getting an air stone but I don’t know the first thing about anything. Everything is trial and error. Do you have a post on air stones? I think my goal is once I introduce Delta into his new habitat is to create a black water tank. I have a pretty piece of mopi wood and have some Indian Almond Leaves. I also don’t want to be buying things for the tank that are going to be useless later.

Not that I am keeping score (but I am!!!). I have divided all my costs into essential and non-essential and my essential costs are near 180 dollars and about half of that. I can see that owning a fish is not a small investment as some people outside the hobby say.

Happy Fish Keeping,

Happy to help, CJ.

That’s a good idea on the lighting. Just be mindful that even “white light” isn’t truly white, the light it gives off is often blue. “Daylight lights” are around 5500 kelvin, but are not typically used in homes, they are more commonly used on photosets and other areas where true color matching are needed.

The good news here is that if the water surface wasn’t completely blocked off then enough oxygen should be able to enter. Because of this, You won’t need to test your oxygen levels, they will be fine. The only time you might need to test your oxygen levels is if you overstock your tank (too many fish) but this won’t be an issue for you.

It could possibly be your candle, it’s hard to say, the only real way to find the problem is through the process of elimination. Skip lighting the candle and if it comes back, then you can say the candle wasn’t the problem. If it doesn’t come back, then it was the candle.

Truth be told, Betta don’t do well with moving current. They come from rice paddies and sloooow moving waters. Water movement from say a airstone can cause stress, which won’t instantly kill delta, but will make him more prone to disease (like how we get sick easier when we are stressed.) A bubbler is just another method of providing surface agitation, they don’t actually “inject oxygen” into the water. If you can achieve the same with your filter on a low setting, then that will work just as well.

If you don’t mind having your tank “stained” a slight yellow/brown color, then Indian Almond Leaves anecdotally provide benefits since it closer emulates the natural environment of the betta. I personally like the look of blackwater tanks but plenty of fishkeepers pride themselves on keeping their water crystal clear. Fortunately if you don’t like it, you can remove the colors using water changes and activated carbon. Just be mindful that your driftwood will also leach color into your aquarium. This can be reduced by boiling it in hot water before adding it to your tank.

It certainly is surprising how expensive this hobby can be. I am not as brave as you. I don’t think I could add up all the costs over the past thirty years, Some things are better left unknown. Just be thankful you don’t have a saltwater tank! Those things add up even quicker!

All the best and please don’t hesitate to ask if you have any more questions!

No more questions, for now. I have been reading your blog which has a lot of answers.

Just one last thank you, and until next time (probably if my tank does not show signs of cycling in the next week).


Hi Ian,

So I’m a bit confused, starting 3.5 gl Betta tank. I’ve had it set up for two weeks. PH at 7 – 8. Shows ammonia at .50, nitrites 0 and nitrates 8. Here lies my confusion, I have not added ammonia and my understanding is when cycling we are trying to achieve ammonia levels of 0 with the same for nitrites and under 40 for nitrates. So why would I add ammonia or do I need to at all?


Hi Bobby,

I’d suggest reading this article from top to bottom. The short answer is:

While we don’t want ammonia in the tank, we need it to grow bacteria that will keep ammonia from fishfood and poop at zero once we introduce fish.

If you are doing a fishless cycle, you will want to add ammonia, as per the instructions in this article.

Hello Ian,

I am back earlier than thought.

So due to my misreading my tests correct the first time, I have been more scientific in my approach going forward.

I can say with confidence my Ammonia levels are right at 2.0. My ph is 7.4 to 7.8 and Nitrites and Nitrates are zero. It is day 12 since my set up has been running, but I will call it day 7 since my ammonia levels have been below 8.0 (or off the chart).

We eleminated the lighting issues that caused the incorrect readings and we got rid of the surface gunk (I have not lit the candle on the same table or put my hand in the tank, so not sure which it was).

But, being a first timmer here I did something that maybe you might have thought about or maybe something you might be able to propagate if you think it will help first time cyclers…

I took a known source of ammonia fee conditioned water and my test tank water with a medicine syringe from the drugstore and put 2.5 ml of tank water with 2.5 ml of ammonia free water and confirmed a reduced level reading. My all tank water test read 2.0-4.0 to me…. but I was not sure.

So, to be sure my eyes were not lying I did the second test. and sure enough I could visibly see a change in color without going in and out and in and out of the house to make sure…

My split water test came in about 1.0ppm, SO now I feel much more confident I am on the right path.

So, I am on day 7 like I said. if I do not see nitrites in the next 7 to 10 days I will be concerned.

In the mean time I have a few questions that have formed in my thoughts.

1) I want to introduce bio rings. is it ok to introduce them now? or should I wait until the tank is cycled? I dont want to risk interrupting the process again.

2) I bought some plant bulbs and they have been in the tank since day 1, nine out of twelve are not showing signs of growth. The bulbs have biofilm all over them. Should I remove them now or wait to see if they cause my ammonia levels to rise as they decay?

3) Since my water changes to bring my ammonia levels down I have not added water or ammonia. My water levels are going down slightly and my ammonia levels seem to be steady, do you recommend adding water to top off OR adding ammonia to bring my levels up from 2.0???

4) I did not have good luck with dr tims bacteria. but I do think it put something in my filter media… that being said I have a brown green looking slime and lots of stringy looking growths. IS THIS A GOOD THING? (but still no nitrites or nitrates)

Thank you sir, Have a great day,

Hi again CJ,

I’m sorry to hear your cycle is moving slower than expected. Not to worry, it’s not at the “something is halting my cycle” stage yet.

Biorings should be introduced ASAP. These are essentially mini houses for your beneficial bacteria. This will allow them to “move in” during the cycle. biorings should be inert and have zero impact on how a cycle progresses.

It’s possible the bulbs are rotting. Since you are controlling the levels of ammonia, anything else that could contribute to ammonia should be removed. At this stage I think it’s safe to say these are dud bulbs. If these are what are commonly referred to as “betta bulbs” then it’s common for a majority of them to fail.

Ideally you want to maintain your 2.0 ammonia. Topping off water is a good practice, if your tank is open topped, evaporation can happen quickly. While cycling, Any water you add/change should be followed up with a dose of ammonia as per your tests.

On your filter, that slime/sludge isn’t your beneficial bacteria (you won’t be able to see the bacteria) it’s likely filtered detritus removed from your tank. This isn’t a bad or a good thing. Your filter is doing it’s job. Rinse the filtermedia gently in fresh, dechlorinated water if this starts to build up too much.

Because these bacterial products contain live bacteria, it’s *possible* that they were dead on arrival. These bottles need proper storage throughout the supply chain and both heat and cold can kill what is inside. This is more common than I’d like. Don’t worry, this won’t harm your tank.

I also noticed you didn’t list the temperature, are you keeping your tank warm enough?

Moving forward, add your biorings ASAP, continue dosing and check back in 5 days after. If you have not seen any movement yet, I’ll help you go over your tank with a fine tooth comb.

Thanks Ian,
I will add the biorings ASAP. my tank temp is pretty constant between 73 and 74 F… I did turn it up today to 75 as I read somewhere here in your blog.

Mean while my poor little betta fish can only look at his new tank through his glass… He is dying to get to his new house (hopefully not litterally).

I do partial water changes every 2-3 days and test his water every day for ammonia levels. He is still happily feeding and blowing bubble nests from time to time.


Thanks for clarifying, everything indeed sounds normal and your betta sounds healthy. It’s just waiting now. I have my fingers crossed that you see some action soon.


I just removed the inactive bulbs and they smell like poo (I think they had to be decaying)… and I just added as many biorings as my little filter could handle.

Thank you for your responses to my posts.

So another thought came to me…

If since I have not added ammonia to my set up since my water changes… It just dawned on me, there is no reason why my ammonia levels should have remained so constant. I did not add any ammonia and my plants are growing very well with the aid of said ammonia. If the plants are using the ammonia I am adding to feed I should have had to add ammonia, right?
In the first few days I did need to add ammonia. Then it spiked off the chart. Then I rebooted but since then I have had a constant ammonia reading with no manual addition. This tells me there had to be some kind of exchange going on as well as some decay. Maybe the bulbs caused my ammonia to climb so high the first time around?

The waiting is the hardest part – (Tom Petty)

Hi CJ,

My apologies here, I assumed you were adding ammonia. Yes, these decomposing bulbs certainly would have been contributing to the ammonia spike, as does any rotting organic. Plants are considerably more tolerant of ammonia than fish. While they won’t use it to feed, it won’t affect them.

Tom Petty had it spot on. Don’t worry, you are not alone. I have done this a hundred times over now. I still hate the waiting part.

Hello Ian, I am on day 8 of following your guide. my ph levels are 7.6, ammonia level is 2ppm and has not yet started to drop. I used the API quick start on day and still no sign of ammonia dropping or any sign of nitrites. according to your guide, it says see you in a week. thhen on step 4 it says check for nitrites after a week(which I did with no sign of them). then it has steps on what to do when they show up. my question is what do I do if after a week I still have no signs of nitrites? do I do a water change or just keep waiting? thank you in advance.

Hi James,

Just to confirm, are you reading your test kit in natural day light? The lighting from indoor lights can drastically throw off the readings. If not, go outside in the middle of the day when you test to compare your results.

Awesome, that’s a great start. Do you have biomedia, such as ceramic rings in your tank? Most filters come with this, but it can be purchased separately, it’s like a home for beneficial bacteria to grow in. If your filter just comes with a disposable cartridge, then there is less surface area for BB to grow. Also, throwing out these cartridges also disposes of the beneficial bacteria, and can reset a cycle.

I am a beginner so I am not 100% sure what biomedia is. I do have a Marineland Penguin 350b filter. im not sure if its too late to add ceramic rings( I don’t even know where to put them) but I did research them and how it is useful in the future. honestly, the filtration was the only thing that slowed me down from getting into the hobby. so much confusion for a beginner. I know I cant just replace the replaceable filter cartridges. there is a empty slot behind each filter. im guessing when its time to change I put the old one in the back and the new one up front so some of the old bacteria catches on to the new filter. please share some of your knowledge on that aspect of the hobby. thank you very much Ian!

Sorry James,

I often forget that others don’t have the same experience as me. Anything that sits in your filter and “filters” is a media. Biomedia is essentially anything that can be a home for beneficial bacteria that sits in your filter. Ceramic rings are an example of this type of media. This media contains hundreds of tiny spaces for the beneficial bacteria to cling too. Beneficial bacteria can’t cling to a smooth surface, it lives on rough, textured surfaces that contain pores.

You should get your ceramic rings ASAP as it’s possible there isn’t anywhere in your filter for beneficial bacteria to set up shop, which may be slowing down the process. There isn’t a whole lot of space in Marineland Penguins for ceramic rings, so you may need to use fine sponge instead.

To help me get a better idea of what else is going on, can you list:

Water temperature (do you have a heater?)

Are you dechlorinating your water before you add it to your tank?

What brand of ammonia are you using?

Is there anything else you have/are adding to your tank?

Is there anything unusual in your tank? (excluding gravel, fake plants)

Are you on well water?

Hopefully we can get to the bottom of this!

yes I have a heater. water temp is 72-74
Ammonia = 2ppm
Nitrite = 0
Nitrate = 0
PH = constant 7.4-7.6

I am using Ace Hardware Janitorial Ammonia as I researched it to be really good and pure. It was a brand new tank. I rinsed it out and let it air dry. I then placed the gravel, decorations and filled it up. then added filter, water pump, thermometer and heater. I then added API Safe start and TetraSafe Dechlorinator. 24 hours later I added ammonia. ever since then I am sitting at 2ppm. In my opinion, I think it has to do with the water temp. I have a Aqueon 100w and it struggles to keep the 36gal up to temp. I just got a 200w and going to crank the temp up 78. I am not on well water. my

I have no experience with Ace Hardware ammonia, but if you are confident that it’s pure and doesn’t contain any additives, then it will be good enough.

While 72 is on the colder side (the BB grows faster at higher temperature) it’s not going to stop your tank from cycling, it may go slower though.

Everything seems fairly normal, Besides adding some type of biomedia, there doesn’t appear to be anything you have listed that is out of sorts. I’d crank the heat up and give it another week.

Great article. Maybe you can help me with my stalled cycle. For reference this is a new 75g freshwater tank. I started out dosing ammonia to around 5ppm. Kept it that way about 2 weeks and no nitrites. I does a bottle of tetra safestart max and the next day I had readings on all 3. I continued to dose ammonia and now 4ppm goes away in 8 hours. My nitrites are off the charts and nitrates stay around 10ppm. A week of off the chart high nitrite readings and I performed a 50% water change. No change in nitrites. Two days later I did another 50% water change and still no drop in nitrites. I always dose prime on my water changes. During this entire time I have add some Seachem stability every other day or so. I’ve heard that extremely high nitrites can stall the cycle and also I’ve heard to not worry about nitrites and it will eventually work it’s way out. Should I continue to dose ammonia daily and just hope nitrites fall overnight. Also wondering if the Tetra SafeStart has my readings screwed up still with the nitrites and nitrates and my tank is actually cycled since the ammonia dissipates so quickly??

Hi Kevin, just to clarify, what you are doing, is your nitrite reading at the higest level? (5.0 on API Test kit?) If you are not noticing any movement when you do a 50% water change, then it’s possible that your initial nitrites exceeded 20. Let’s say it was at 30 ppm.

1 x 50% water change would drop it to 15 ppm
1 x 50% water change would drop this again to 7.5 ppm

This would show as no change on your test kit for nitrites (it would still show 5 ppm. Could this be what has happened?

I would work towards getting your nitrites down to a level where they show up on your test. It might take quite a few water changes for this to happen. Don’t forget to re-dose with ammonia as this is also diluted with each water change.

Hello Mr. Sterling. Just wondering, what is the best method that you prefer of acclimating new fish? I am planning on getting a betta fish soon. I have heard drip acclimation is good so is the float method where you add more tank water. Thanks! -Ben

Hi Ben,

I personally use the drip acclimatization method. It may be slower but it significantly reduces the chance of shock.

Hello Ian,
Just checking in…

My tank has been set up for 20 days now…
I am on Day 13 after learning how to read my tests properly and heavy water changes…
And I am on day 7 since removing all organic matter (Plants and bulbs)…

My ammonia is at 2.0 and the only time I add more is when I replace my evaporated water with pre-conditioned water.

My PH is right around 7.8 – 8.0…

Nitrites and Nitrates are zero and nowhere to be found…

My water temp is steady at 75 F…

So, I am keeping my happy nest making betta in 1.75 gallons with most of his plants. He seems to love it. He rests quite often on his plants and sometimes hovers right below his very large bubble nest. With the amount of plants temporarily sharing his bowl the ammonia levels rise very slowly. After a PWC it takes about 4-5 days to get levels above .25ppm. His tank does not have a filter or heater but the LED light puts out enough heat to keep his water at 70 F.

I am just bored and hoping to see movment in the 5 gallon in the next day or two. I am using Dr. Tim’s ammonia for doseing. I have the filter and heater running with substrate and a few small pieces of decor… I never seem to have to add ammonia. Is this a bad thing? I take it that it means nothing is eating the ammonia as planned.

I fixed the filter issues to aggitate the water a little more and the film no longer accumilates on the water surface. I added bio media. I removed the rotting bulbs that were spiking my ammonia readings (your right they were the ones called betta bulbs, although three of them have taken off and Delta really loves the biggest of the three to rest on and build his nest).

Not really looking for any other suggestions unless you have one. Just writing to share the misery of the nitrogen cycle…


Hi Again CJ,

Thanks for the upadate!

If it were me, the only thing I would do differently is try and lower the pH slightly, to get it around low to mid 7. However this can be complicated and I generally don’t recommend messing around with pH too much if you are not familiar with it, it can make things exponentially worst as it bounces around. 7.8-8 is still within beneficial bacteria tolerance.

If your betta is making bubble nests then that is a good sign he is happy. Stressed betta don’t normally make bubble nests – so that’s a relief. However, be mindful that betta temperature should ideally be a little warmer 74˚F on the low end. However, if your betta is thriving then this should be the least of your concerns. Just be careful when you add him to your new tank, as it will be warmer, he will need to acclimatize first to avoid “temperature shock”

The ammonia not going down isn’t a bad thing. It just means the beneficial bacteria has not begun to form yet. At the end of 2 weeks, it would be a bad thing, as something is preventing the beneficial bacteria from appearing in your tank. At this stage it’s trial and error, making adjustments and removing things until it appears. This sucks. A lot. I have had to do it twice and don’t wish it on anyone. (in one instance the substrate was contaminated, the other was my biomedia appeared to be killing them and swapping it out solved the problem) I have my fingers crossed yours kicks off in the next few days 🙂

Hello. So I have been following all your steps to a T! But I am starting to see some strange changes in my water. I bought a little 10g tank about 3 weeks ago, decided on a fishless cycle, bought the Fritz and master water test kit suggested, among all the other starter things needed for the tank. My pH is currently 7.6 most days, I get an occasional 7.8. My ammonia has been riding at a 4.0 ppm and this week to a dive to a 2.0 and tonight is a 1.0. One week ago (2/24) I got the slightest hint of nitrites, and they have slowly been increasing, tonight I got a 2.0 ppm, but along with this 2.0 of nitrites I did a test of nitrates and got 40 ppm. Final read on the 3/3 test, pH 7.6, ammonia 1.0 ppm, nitrites 2.0 ppm, and nitrates 40 ppm.
I guess my question is, since my nitrites aren’t declining yet should I be adding more ammonia?

Hi Holly,

That actually all sounds really positive! Congrats, your cycle is progressing well. I would add more ammonia as it gets depleted. You can re-dose to 2ppm for now if you wanted, and as it drops quicker increase back to 4. Or re-dose to 4 right now, it makes little difference. You just want to make sure there is ammonia for the first bacteria to feast on.

This is so reassuring! This whole process gets me worked up since I am so new to it! I have since been re-dosing almost daily up to 2 ppm, last night to 4 ppm, but it still seems to drop to 1 every day, nitrites are still holding at 2.0 ppm, but I am just glad to know things are moving! Thank you for you amazing post, and your help!!

It can be a lot to take in but hang in there, it sounds like you are doing great. If your ammonia is decreasing then it’s going somewhere, and the fact that nitrites are testable is a good sign. You might want to test your nitrAtes, as well, just to see what is happening there. Not everyone experiences a linear progression through the steps, sometime it kinda all happens at once. From here it’s just patience. If anything seems amiss, drop a line here and I’ll advise to the best of my ability with troubleshooting. Good luck!

So since I last replied I have been testing for NitrAtes daily. At first it was a just for fun and didn’t expect anything out of it, but literally 3/5 had 5.0 ppm with NitrItes of 1.0 ppm and ammonia at a 2.0 ppm. The following day my nitrAtes took a huge JUMP! They jumped up to 20 ppm with nitrItes of 2.0 ppm and I have had to add ammonia daily because by morning I am at 0.25 or 0 ppm (I keep it at a 2 ppm daily and test probably 3 times a day, ones first thing in the morning, once 1 to 2 hours after dosing and once when I test for everything else in the evening). My nitrItes have been holding at a 2.0 ppm since and have not moved. My nitrAtes have slowly moved up and are not sitting at an 80 ppm for the last 3 days (I know that is super high). Am I still just in the waiting game?

Daily testing is more than enough, although there is no harm in doing it more frequently, I would still only be adding ammonia once per day, as if you were taking a single reading.

Once nitrates start to climb that high, I generally perform a 50% water change to get the back down. When you say nitrates have been at 80 for three days, they haven’t really, they are climbing (hopefully) but the the next marker on the test kit is 160. So the result could actually be anywhere between 80-160. If you look at your test kit color chart, you’ll notice that the lower ranges are closer together, making it easier for you to determine just how quickly nitrate is rising.

A 50% water change will roughly drop all chemicals (ammonia, nitrite and nitrate) in half, which will allow you to better gauge what is happening. This water change won’t affect your cycle (don’t forget to condition the water before adding it) but you will need to re-dose with ammonia to reach the desired level after performing the water change.

Otherwise, yeah, it’s still just a waiting game. Unfortunately, much of keeping fish just comes down to waiting. It’s part of what makes it such a peaceful hobby.

Hi- I didn’t see a button to comment regularly so I just decided to reply to a comment, so sorry if its in the wrong place. I also have a question about adding ammonia regurarly. I attempted to do a cycle to my 5.5 gallon tank, its been 6 weeks now and I somehow forgot to keep adding ammonia, so my cycle has been stuck at 0ppm ammonia and a super high nitrite reading. So I did a 50% water change today and added in some ammonia (2ppm), I still have some nitrites (1ppm) and nitrates(1ppm) too. (And some beneficial becteria I’m guessing) I’m not really sure what to do next since my cycle is already started, once my ammonia drops to 1ppm should I put in more to keep it at 2? Some more step by step would be great, and thank you for the article it is the least confusing one out there.

Hi Tessa,

I’m glad to hear that you found the guide useful. You are on the right path. You essentially follow the steps here still, since you are waiting for that first bacteria to appear. You are essentially at step 3 in the guide above. You now have to wait a week or two for it to start decreasing. I’d test daily so you can see what is happening and re-dose with ammonia to keep it at your original dosage. Unfortunately, there is still some more waiting for you before you can add your fish. But hang in there – you’ll get there!

I have a question I am saltwater but know cycling is similar. I don’t hold you responsible whatsover for your answer. Why do these companies like API, and many others tell consumers that they can cycle a tank and add fish in 24 hours? I know of no one (about 10 people) that have had fish survive much at all even using those products. As you stated, once you add the fish the ammonia starts right away (if it is day two). I think it is deceiving, perhaps it is possible if water changes are done daily.

You mention that when you leave the tank empty and no more ammonia that at the end of the day, the bacteria die off. I have left my tank for two weeks now after it cycled as I was waiting for some cash for fish. Should I possibly add a snail or two from another existing tank so that the bacteria can feed? If the tank is new (it took me 32 days to cycle with live rock). Will the snails have enough food to eat in a new tank as to me it is rather heartless if one starves them. As I won’t be home for the next five days or so.

Any thoughts are appreciated, I think this hobby is like crack. You start it and you just keep going and going. As for Seachem Prime it saved my tank (I learned about this product from you and used your affiliate link a couple months ago) I know I am saltwater but after research, it is the best on the market.

I had a five gallon nano tank with a auto top off. I just had a shrimp and four snails. I didn’t know it but the ATO was put in wrong by me, I tested it never in the aquarium (duh but it did work outside the aquarium) and put the sensor in the main part of the aquarium as opposed to the back with the filters. Anyhow I left five days, and set a feeder. I came back that the tank had 3 gallons of saltwater, saltwater spike from hell to 1.35. Yet, ammonia was 0. The water had evaporated and I had no filtration except the power nozzle. Before I went on my trip I put in the regular dose of prime and it is my true belief that it saved the whole damn tank, but I will never try on purpose as one of the snails was dead 🙁 which was on me and I pulled him out. I have no idea how long he was dead but the point was my ammonia in a little tank was showing zero :). As I reckon that the tank ran for two days with no filtration as the water went dry. How the creatures took the salinity spike I have no idea.

What was interesting and Randy I think his name is said in a forum where this transpired to someone else (salt creep) that higher salinity typically causes an algae bloom. Can I say that three days later the snails went on strike as the algae went nuts but were good now :). Just wanted to share that story as man I can’t believe I didn’t test the thing in the aquarium before I left and I would have felt terrible if I killed everything.

Hi Russel,

I can’t speak for companies like API or big chain pet stores, where these recommendations are common. One could speculate that in a world where no one wants to wait, and cycling is a slow process, that there is money to be made in promising an instant cycle to beginners who don’t know any better and won’t follow up by using a test kit to monitor their tank. Sadly, by many, because fish don’t show suffering in the same way that a dog, cat or similar pet would, they are seen as somewhat disposable. I and many others are of the belief that this is wrong, but it’s a trend that won’t seem to die.

If you have left your tank alone for two weeks, it is possible there has been some beneficial bacteria die off. This will be easy enough to spot if you add ammonia and it doesn’t disappear.

Adding a snail or two wouldn’t hurt. Admittedly, I am less familiar with snails than I am fish, but I would assume that like fish, snails could go some time without feeding. Most fish can happily last up to a week without a meal. In the wild, they wouldn’t get a hand fed meal each day, food would be far more difficult to come by and as a result had adapted to survive days without feeding. We spoil our fish compared to how they eat in the wild. You would need to research the exact feeding habits of your snails, as I cannot give you the exact advice here.

I am really happy to hear you are enjoying the hobby. You are right, it’s addictive. I started with neon tetra and shrimp over 30 years ago and I’m still enjoying it as much now as I did back then. It sounds like you had quite the adventure with your nano, you did well to save it, that’s really awesome on your part.

As for Randy, you are likely talking about Randy Holmes-Farley, he has been doing this for quite some time now, well regarded and I would trust his analysis.

Thanks so much for your support. It seriously means the world to me!


Day 29… I have Nitrites and Nitrates… YEAH!

So, long story short, I was about to start the cycle all over because I just came home from a 5 day trip with no testing on the tank… low and behold MOVEMENT

So I am at 1.0 ammo; .50 NI; 5 NA; just under 8 ph; 78.1 degrees!

I just added pre-treated water to replace evaporation, and 2 drops of dr tims ammo and will test again soon to make sure I stay at 2.0 ppm.

I thought it was odd last night, I thought I saw NI but tested at night so no natural light, so I thought it was just my eyes again. It must have been just about .2 NI and today .5!

But my NA is at 5. I just read your comment above. So, NA at five is ok with NI at .5 and ammo at 2.0???

I can see the light, Thank you!

Hi again CJ,

That actually sounds incredibly positive. What a relief! If your ammonia has dipped, you have nitrites and nitrates are increasing, then your cycle is progressing, slowly, but it’s definitely progressing. Just keep topping up your ammonia as it dips and the rest is a waiting game. Hopefully it’s not too much longer now!

Hello! Newbie who just started cycling her 55 gallon freshwater tank, fish-less. I’ve added the ammonia as you suggested; I’m confused about this initial first week- do I have to keep testing the ammonia levels and DO anything if they aren’t a certain level, or just assume once I’ve done the initial dose of ammonia to get it to 4ppm that I’m good to sit around and wait?

Can’t wait! Thanks

Hi Lori,

I suggest daily testing, this will give you a greater understanding of how your specific cycle is progressing, to an extent, everyone experiences them differently. From here, you react according to your test results and go from there. I know that waiting sucks, but it will be worth it!

I have a couple questions as I am perplexed and cannot find answers ANYWHERE pertaining to my situation.
I am a semi noob for freshwater. I left my last set up when I moved cross country- and 3 years later have decided upon a new one.
I understand (pretty much) how this process works, and I have set up to do a fish less cycle on a 55g freshwater tank.
Every thing is up and running.
I am 13 days in. My pre conditioned tap water runs at .50 ppm ammonia straight out of the tap, 8.5 ph, no nitrites or nitrates (I went ahead and fully tested my tap water pre set up)
Fully followed this guide, and everything was plugging along fine. Started this process 2/28.
4 days ago, (3/8) my ammonia dropped to 2, and my nitrites appeared at .25ppm.
I was hesitant to half dose ammonia at this point because the nitrites were just appearing, so I retested the following day (3/9)and had 2ppm ammonia and .50ppm nitrites.
I went ahead and half dosed the ammonia,double checked the readings after 1.5 hours to determine that a half dose did not take me over 5ppm, and the following day (3/10)when I tested my ammonia was at 4, my nitrites were ZERO.
So I tested Nitrates. They were at 20 ppm.
Same for yesterday the 11th, and today the 12th.
My ph has held steady through this whole process.
Am I on the right track? Or do I need to do/change something?
I’m unsure how i can have so many nitrates when my nitrite levels are at zero, and my ammonia level is holding steady at 4.
Is this a just wait it out approach (i have plenty of time that’s for sure.its not ready till its ready) or is there something i need to do to balance this out?
I forgot to add- i am using an API freshwater master test kit, and the ammonia is fritz pro aquatics ammonium chloride
Any advice will be helpful and appreciated even if it’s just wait it out, just to know I am at least on the right track.

Hi Debbie,

It’s hard to say without more waiting. If you look at your nitrate test kit, you’ll see that as the numbers go up, the range increases. while there is just a5ppm difference on the low end, the next step up from 20 is 40 ppm. Just because your test kit reads 20, doesn’t mean it’s stuck there, it could read anything from 20-40. Also, I just want to confirm that you are reading your test kits in natural day light (inside lights can make colors look different.)

While the lack of ammonia decreasing could be a concern, it would depend if any parameters or equipment or additives have changed at the same time. Simply adding more ammonia to 4ppm won’t stall a cycle.

Thanks for the reply!
No equipment jas changed, and I always read in natural light.
I have no issue waiting it out provided that’s the recommendation at this point- as long as SOMETHING is happening in there it can take all the time it needs- I knew going in to this that it would take as long as it takes to start from scratch.
I just wasnt sure if there was something I should be doing, or shouldn’t even at this point!
I will keep plugging along, enjoying the sound of the tank and waiting for the day shes cycled and ready to add beauty too!

Keep in mind that you cal always perform a 50% water change. This will roughly cut nitrites and nitrates in half, bringing them back to the lower range on your test kit, making it easier to keep track of progress day by day. Water changes do not slow down your cycle – the beneficial bacteria lives in your filter media, it is not free floating.

Also keep in mind that a water change will also reduce your ammonia. So re-dose after any water change as per your test kit.

It sounds like you are approaching this with the right mindset. I have my fingers crossed that it’s not too much more waiting now.

Hi Ian,

I am competing a fishless cycling in a 45 gallon tank that holds about 40 gallons of water due to the rocks and decorations inside the tank. I am on the 16th day of cycling. My ammonia ppm is at 1.5, my water ph is at 7.5, my water temp is at 77 degrees and no nitrites yet. Should I add more ammonia to increase it to 4.0 ppm or just leave everything for now? I am just surprise not to see any nitrites yet, but I am trying to be patience 🙂

Also, on the 3rd day after cycling my tank water is cloudy and still is at this time, is this normal? I read this is do to the bacteria boom.

Thank you for all your help


Hi Ron,

Did you start at 4ppm? If so, I would monitor your nitrates as well, to see if these are going up. Not everyone experiences the cycle in the same way. Sometimes it skips from nitrites straight to nitrates. So this is a possibility. If you didn’t start with 4ppm, I’d increase the ammonia to 4 just so you can monitor it decreasing, as this means progress is happening.

At this stage, I would be leaning towards the white cloudy water as being bacterial bloom. This is normal and should go away on it’s own.

Hi Ian.

Thank you for your reply. My nitrates are at 0ppm as of today and when I started my cycle, my ammonia started at 4ppm and my water ph started at 7.0. I did not test neither the nitrites nor the nitrates when I first stared the cycle two weeks ago.

Thoughts or advise what my next steps should be at this time?

Thank you in advance for all your help.

If your ammonia has decreased, and you didn’t perform a water change or use an ammonia removing product, then it is possible that the cycle is further than you think. Ammonia doesn’t just disappear – it has to go somewhere.

If you are not responsible for the ammonia decrease, then my first thoughts is the test not revealing you actually have nitrite or nitrate. What are you using to test your tank? I would double check that you are following the instructions and reading the test results in natural day-light. The lights inside your home can impact the colors shown. I would Also check the expiry date on your test kit, an expired test kit is the least likely cause, but you never know.

Hi Ian.

I am using the API Master Test kit as you have posted in your forum. I checked the expiration date of my test kit and the solutions expire in 1/2023 so the test solutions are good. I went out and purchased another test kit (The test strips) and the nitrates came back positive, the nitrites came back negative, my water ph is 7.2, and zero chlorine. I added less than a 1/2 tsp of
Fritz Pro Aquatics Ammonium Chloride (ammonia) and I will check all my readings again in 24 hrs and see what readings I get at that time. I will let you know what my readings are within the next 24-48 hrs.

Thank you

Hi Ron,

That’s unusual, If you are confident that you are using and reading the test kit (including shaking the bottles, shake them more than it says and vigorously too, for about a minute) then it’s possible that you have a faulty product, which is very unusual. I’ve been using this test kit for years without issue as have thousands of others. All cases I have personally been involved in where the tests didn’t work came down to user error. However, I have to trust your judgement here.

If you have nitrates, then it’s possible that the bacteria that converts nitrites to nitrates has established enough that it is eating the ammonia fast enough that it reads zero. This is good. I have my fingers crossed that this is the outcome. Unfortunately, it will take a few days of waiting before you will know for sure.

Wow!! Ian you have a real knack for teaching. Thank you for all the valuable information. I’m 4 days in and dedicated to waiting till this new tank fully cycles. I have a smaller tank now and felt as though it was time to upgrade. How do you feel about introducing used filter media to my new system. Would that speed up or impede the process?

Hi WhiskeyChris,

Thanks for the kind words. Your thoughts are correct here. Introducing “used” filter media will absolutely speed up your cycle. It’s why many independent fish stores sell pre-cycled sponge filters, to kickstart the cycling process. Depending on what the used media is, I’d place it in a filter media bag, then place that on top of the new, uncycled media in the new filter. This way it can easily be removed. Then, once the tank is cycled, I’d remove it and fill up the rest of the space with more of your new media. The reason you should remove the old media, rather than leaving it inside is that it will deteriorate at a different rate. Ceramic rings, for instance, will eventually get old and crumbly. While this can take years, it’s easier to only have to deal with the problem once.

As for how much quicker this will make the cycle, there isn’t really a clear answer here. It depends on the size of your tank, the amount of used filter media used, the amount of beneficial bacteria it contains, etc. The only thing certain is that it will speed up the cycle.

Thanks for this great article! I’m starting a 36 gallon tank and have been very nervous about the cycling process – your clear explanations make me feel more confident and I’m /almost/ eager to get started. My question is about water. I live in the country and have a well, which means no chlorine, fluoride or other additives. Do I need to test differently, and should I expect different results? Thanks in advance!


Hi Hebe,

Yes, you will also need to check your KH (KH guide here as the hardness of well water will vary according to natural mineral deposits present. This in turn can affect your pH, read that article, it will get you up to speed here.

Next, depending on where the water feeding your aquafier comes from, there could be elevated nitrate levels from agriculture, it might only happen after storms or it might always be present. For this reason, you should run base tests on your water before adding it to your tank, so that you know if the appearance of nitrate is due to the tank cycling or whether it was there from the start.

Assuming there are no chemical runoff in the water, and you have done the above, the cycling process will be very similar to the above. If you have a local fish store, or know other people who raise fish in the area, they will be able to provide valuable insight here, since they are using the same water source as you. Good luck!

Hi Ian. Just about to start to cycle my 10 gal tank and I was wondering how I would go about cycling with fish food as I currently have no access to getting ammonia specified in the post?

Hi Nicole,

Just add a pinch and it will begin to break down, releasing ammonia. Measure with a test kit and add more accordingly as your ammonia decreases. Otherwise it’s a similar process, you just won’t be able to dose an exact amount of ammonia. Similarly, a raw shrimp in a stocking will also work.

Hi Ian,
I have been following your instructions for a fishless cycle. Everything progressed as anticipated, until step 4. I have been waiting patiently for about 2 weeks now for the nitrites to drop, but they just won’t! The ammonia is getting metabolized rapidly, so I am adding about 1/2 dose daily. 24 hours later, the ammonia is 0.25 ppm (never zero). Once the nitrites appeared, they peaked at 2-5 ppm and have been there for ~2 weeks. Out of curiosity I’ve checked the nitrates a couple of times and they have been at 5 ppm. pH is 7.4-7.6.

Is there anything I should differently? Or just keep adding ammonia and wait it out?

Thank you so much!

Hi Kristin,

I’d move on to check your nitrates. If these are going up, it’s possible that the nitrites are being consumed at the same rate they are being re-stocked.

Also, are you checking the results of your test kit in natural day light? Lights from inside your house can make the colors look off, resulting in an inaccurate measurement.

Hi Ian,

Thank you kindly for your reply. I have checked my nitrates a few times over the past 1-2 weeks, and they are staying at 5 ppm. I’m essentially in a holding pattern, where the ammonia is getting metabolized rapidly but the nitrites are staying at 2-5 ppm and the nitrates at 5 ppm. I am checking the test kit in natural day light.

Would you suggest that I do anything differently, or just keep giving daily ammonia and waiting?

Thank you,

Hi Kristin,

A couple of follow up question, you have not performed a water change during this time either? Water changes lower the amount of nitrite and nitrate in the water.

Next, do you have any nitrite or nitrate removing products in your aquarium? This could also be impacting your results.

Next, are you shaking your test kit enough. Follow the instructions and when it says “shake” give it a vigorous shake for a minute. Re-test and see if that helped.

Finally, can you test your tap water prior to adding it to your aquarium. 5ppm isn’t outside the realm of what some water sources contain. This will let you know whether the 5ppm is from your nitrites or whether it has been there from the start.

The thing is, all that ammonia has to be going somewhere. So if it isn’t being removed by anything you have added or are doing, then it should eventually become nitrates.

At this stage I would cross off the above in regards to troubleshooting and re-test over the next 3-4 days for nitrite and nitrate movement. While it is getting on, it’s hardly at the stage where you need to panic yet.

Hey Ian,
So here is a quick update on my 10g tank. I have had it for 8 weeks now and the cycle is STILL going. I check the levels daily. I am still stuck on my nitrites! My ammonia drops out every day now to 0 ppm, but for the last 2 weeks my nitrites have been at 5 ppm, making me think they are probable higher. We have done 3 water changes hoping to bring them down, along with the outrages nitrite levels we have an outrages nitrate level of 80 again (or higher as we had discussed before). We added some new filter media, the matrix because no one in our area sells ceramic rings or bio balls. I read your post about these very carefully before buying anything and did a lot of reading about matrix before buying it as well. I guess what I am getting at is that I am just stuck… I am so stuck as to why this will not progress. After water changed the nitrites do not come down at all, the nitrates do but about 5 days later we are right back up to that 40 to 80 range.

I might have also gone a little nuts and bought a new tank to drive myself crazy and start over with a brand new cycle….. This tank came with the imagitarium biological booster, I haven’t used it yet because I don’t know enough about it, and I have seen so many conflicting reviews. How do you feel about these products?
Thank you for your help!!!

Hi Holly,

Good to hear from you again. Not so good to hear about your predicament. Although, I have a suspicion that your tank is actually cycled.

If the ammonia nitrates are that high, then ammonia is indeed being converted to nitrates. Are you sure that the nitrite readings are correct? I’m beginning to think your test might not be right. If ammonia is going down and nitrates are going up, then everything seems normal besides the stuck nitrite reading. The fact that this reading isn’t even dropping even after a 50% water change is another clue that your tank might actually be cycled and it’s the test that is wrong. If I were in your position, the test is what I would zero in on.

On the filter media, there is nothing wrong with Seachem Matrix. You chose well.

On the beneficial bacteria boosters, I sit in the camp that doesn’t use them. That’s not to say I am against them. It’s just that I have never seen a product speed up a cycle 100% of the time. Or even 80% of the time. You see, beneficial bacteria are a living organisms and due to storage (say cold weather) they can be dead before they even reach your tank. Also, there are different strains of beneficial bacteria. Dr Tim’s and Tetra Safe Start (it’s the same stuff) claim to have the exact beneficial bacteria that forms in your filter. Other brands have different strains that they claim are better. Who is right? It’s hard to say. But until I see a 100% success rate at speeding up a cycle vs. going without, I don’t see a need to spend extra money on what is already a hobby that can blow out in costs.

More specific to you, if it’s imagitarium, I’d personally avoid it. Based on my lifetime experience, and reviews of various products, imagitarium is always among the worst performing in any product category. Because of this, I don’t trust the brand as a whole.

I am at a loss again! Got a new test kit for nitrites thinking that I got this cycle thing down now, and we were tackling these weird problems! Did my daily test, EVERYTHING WAS 0!!!!! Literally everything! So I went ahead and moved on to step 6, dosed my tank with the same amount I used on day one. So at 24 hours later my ammonia was sitting at 4 ppm still, my nitrites and nitrates were still 0, my pH is 7.8. I checked again this morning (36 hours since it was dosed) and my ammonia is at 2 ppm, but still no nitrites and no nitrates. WHERE DID IT ALL GO!?!?!? I am getting so discouraged now, and I know my tank did not sit with 0 ammonia for more than an hour. Any advice on this crash?

Thank you, Holly

Hi Holly,

I’m a little confused here, was this the first time you tested with the new test kit? And did you test with the old kit to compare?

I only ask as Nitrates don’t just disappear. Like ammonia, it has to go to somewhere. Generally, the only way you could have removed nitrates is via a water change. If your nitrates were 40-80, and the only thing you have done is add ammonia, then the nitrates should still be there.

Are you able to re-test and confirm?

While it it certainly is possible your cycle has stalled based on the ammonia not going down, the fact that nitrates have disappeared shows that there are testing problems that we need to identify and fix first.

As a last resort, many local fish stores also offer water testing services, to see what is actually going on in your water – but you’ll still need to address the testing at home.

I bought a whole new kit. Compared the two, and am getting the same results. 0 nitrites, 0 nitrates, and 2 ppm on ammonia. My fiance now claims he did a 25% water change on 3/16 while I was at work but didnt write it down (because I track everything). I took a sample to my local fish store to test and they got the same reading I got on both my home kits. They basically told me to start over. I’m so discouraged right now and ready to give up.

Hi Holly,

I am stumped by this. A 25% water change should only drop the nitrates proportionally, in this case, lower them by a quarter. Something else is going on here. Did your fiance dechlorinate the water? Because chlorine will kill the beneficial bacteria.

I can only go off the information you have provided but the summary from my point of view is that in three days, your nitrites and nitrates have dropped to zero and your ammonia has stopped decreasing.

Both the nitrites and nitrates should still be at testable levels, even in a crashed cycle.

I do have to ask, what else has happened since the ammonia stopped decreasing? Something has to have been added, removed or changed for nitrates to go from 40-80 to zero. This needs to be identified as if you are going to start from scratch, you don’t want this same incident to be repeated.

Don’t give up! It’s certainly frustrating but we have all experienced extended cycles and crashes in the past. It sucks, but with determination, I am yet to come across an instance where it couldn’t be overcome.

The only things that have changed in the tank is on 3/14 we added matrix to the filter, he did the 25% water changed on 3/16 and did dechlorinate the water, I did add my flourish tabs when I got home from work not knowing the water change happened. We changed out lighting yesterday because out new hood came but that was after all this happened. Other than that I’ve done nothing differnt at all. The aquarium gods are mad at me for getting a second tank before finishing my first cycle I guess.

Hi again, Holly.

Adding seachem matrix shouldn’t make a difference, unless you removed any filter media in order to add it (the beneficial bacteria can live in sponge, filter floss etc. too)

Otherwise flourish tabs and lighting are harmless and won’t affect the cycle. Based on what you have said, I’m absolutely stumped as to what could have gone wrong here. I’m so sorry that you have had to experience this.

Been following your blog for the past two weeks…Very much appreciate this thorough guide greatly!

Long story short: I’m on Step 3, Day 6. Ammonia level has dropped to 1 ppm after a few consecutive days of being in the 2-4 ppm range. Am I in the right- this is normal until day 8 and I begin testing for nitrites?

Hi Jennifer,

I have some good news for you: Everyone experiences the cycle at different speeds. You are likely further along than you think. If your ammonia is dropping, then it’s likely nitrites are already there. You can move to the next step!

Thanks….I’m still rolling along! Currently on Day 9…For the past 2 days, however, I’m getting a negative readout for nitrites. Is that normal? I know they’re bad too, just like ammonia, but I got the impression they are par for the course for stage 2.

The ammonia had dropped to the point that I went ahead and added a small dose of ammonia on day 7 (half of the amount I put in originally – a fourth of a teaspoon) as I was concerned that the levels would go below 2 ppm and it looked like it was headed in that direction and didn’t want to throw the cycle off.

But still getting the pale blue (0 ppm) for nitrites…Do I have to wait for them to show up eventually? Any advice?

The truth is everyone experiences the nitrogen cycle slightly differently. For most, nitrites slowly build up over time. A few people, however, it will stay at zero while nitrate goes up and nitrates go down. I’d test your nitrates over the next few days to see what is happening there. If it’s increasing, then everything is progressing as normal.

Based on the info you have provided, if ammonia is decreasing, I don’t see anything to worry about yet. Just more waiting. Hang in there!

Hello! I just wanted to stop by and thank you for this article. After months of researching and not being sure how exactly to cycle an aquarium, it finally clicked for me with these clear instructions.

Hi Elizabeth,

I’m glad I could help, this is the exact reason why I created this guide. If you have any further questions or trouble following these steps, please leave a comment here and I’ll try help to the best of my ability!

First, I just want to say I love your instructions! They are so clear cut. Thank you!
I do have one question. I am in the process of setting up a new five gallon tank for my one Betta. I filled the tank yesterday, added the prime and waited the 24 hours. I just got the ammonia in the mail and an ready to add it to start the cycling process. I have an existing 2.6 gallon tank which I added a second filter to about two weeks ago. I would like to add this filter along with some substrate to the new tank to hopefully accelerate the cycling process. My question is, at what point should I add the second filter and substrate to the new tank or does it matter? Thank you so much!

Hi Ursula,

Excellent question! It doesn’t matter when you add your “pre-cycled” filter and substrate, although to get the full benefits, you would want it there from there very start. This way, any beneficial bacteria in the added filter and substrate will spread to your new filter from the start.

Hello Ian,
Just writing to vent.
Cycle crashed… I don’t want to do this anymore!
I had 6 days of result were Ammo was 0 after 24 hours at 2.0 ppm Nitrites never showed signs of slowing Nitrates either. Both were off the scale on day seven of 0 ammo performed two 90% water changes to watch how fast NI and NA increase by the day end both were off the chart again. (after water changes and math, NI were about 30 and NA were over 200 then product change and water change)

I ran out of tetra aqua safe for beta (small bottle) had a coupon for aqueon water conditioner after the first use ammo stop metabolizing and NI and NA are totally still…

I want to give my son’s fish away and smash my tanks…

Meanwhile the fish is living quite well since Jan 15 2019 in a 1.5 gallon bowl with a jungle of aquatic plants.

Please talk me down. I am about to start my tank over with fish in… I am sure he will like it more than where he is now and with weekly water changes I am sure he will be quite happy.

I would still monitor water quality but just not have an empty tank that my in-laws and other relatives laugh at me for having an empty tank next to my tv in the living room for months, while the fish is living in another tank quite happy.


I am going to give my tank two days to show me the cycle has stalled and not crashed then I ditching it all.

Hi again CJ,

I’m terribly sorry to hear that this experience has been frustrating. I’d be lying if I said I said that we haven’t all been so frustrated that we want to throw in the towel.

If I understand you correctly, you are saying that your both your nitrites and nitrates kept going up and up over all this time? I have never come across an instance where nitrates kept going up exponentially, there has always been a ceiling before they drop back down. Even in the comments here, no one has reported such an oddity.

I have no experience with Aqueon water conditioner, but I am incredibly doubtful this stalled the cycle. Did you use the appropriate amount of water conditioner when performing the water changes? I’m just checking as killing the beneficial bacteria with chlorinated water is incredibly common.

Also, on the water conditioner front, I recommend using Seachem Prime, it’s ultra concentrated and will last soooooo much longer than Tetra Safe Start or any other water conditioner. It saves money in the long run.

I’m sorry to hear about your family not “getting it” I’m also often questioned by new guests and family as to why there are empty tanks with no fish (in the cycling phase) I got tired of explaining that years ago and just now say “I have a rare fish on order, it won’t get here for a few months”

Moving forward, if you do want to start your tank with a fish in it, then you’ll need to pay really close attention to the water parameters, it’s daily testing for a few weeks with either regular water changes or regular dosing with seachem prime to neutralize the ammonia, nitrites and nitrates before they balance out.

Only you know what’s best for you here. I think you should give it another go, either fishless or fish-in. It would be a shame to see you give up on a hobby that is so rewarding just because the first step is a doozy. It definitely gets easier and more relaxing!

Wishing youa all the best!

Hello Ian,
Thank you. I am trying. Probably harder than I should be?

The problem is I am attached to the fish now. I would be sad to see him pass or give him away, but really in the end its one small fish. I am sure I will get over it. It is harder to get over taking care of a tank with invisible creatures that you can’t tell they are there and then you know they arrive after two weeks or more of time and patience. Then the colony grows bigger and you are right near the last few days only for the whole thing to get wiped out. I have spent about 50 days on learning reading and cycling a tank with no end product. Start over now and I will finish, LUCKILY, after 3 months or more, collectively!

THIS IS MADDENING, I should have got my kid a cat like he asked for! (I am mildly allergic to cats, less pain and suffering than this)

So, I am going to give this one more try then I really don’t care what happens… Oh and just so you know I do not put any of this on you, LOL in case you had any thoughts.

Take 2
What should I do?
Should I empty the tank so that my NI and NA will read 0 (there are residual readings from the first colony)? Should I change my biorings and filter out? Rinse the decorations off?

Or should I just leave everything as is and dose ammo back up to 2.0 and let sit until it starts to be metabolized again?

Extremely frustrated,

I FEEL YOUR PAIN! I’ve messed up the cycle so many times and have been trying to cycle my tank for 10 weeks now, I’ve already messed up the cycle twice and I think I’m messing up for a third time! I have my betta in a temporary 2.5 gallon tank and have been doing 20% water changes (every. Single. Day. For. Six. Weeks. Now.) until I can put him into his 5.5 gallon tank because I’m terrified that the ammonia in his tank will get too high. I told my self before I went into the pet store that day that my tank was not ready and that I can’t get a fish. Well that worked out lol. The funny thing is that fish are supposed to be easy pets, but this is the most work I’ve ever done for a pet before. But I love my little guy so much so I just have to hang in there. Good luck.

Oh, I meant to address some of your questions as well, sorry. My NI was over 5 after the third day of them being present. I charted them to grow up to 20-30 by the 7th or 8th day of arrival. I thought I would start to see them decline in the next 2-4 days based on your graph in this post. At this point I ran out of my tetra water conditioner. I then used aqueon water conditioner and dosed at 5ml per gal instead of 5ml per 10 gal. I think this is what did it maybe? Left the tank like this after a 4 gallon or 80-90% water change for one day. Then I did it again the same mistake for another day, 80-90% change at wrong dose. AAAHH. Then I realized what I did. Now I am hoping I stalled but testing today looks like a total crash!!!

I am about ready to take the aqueon product back to the store or dump it and go back to tetra or try seachem prime like you said.

Here is a secondary thought and issue.
I have my betta in a 1.5 HEAVILY planted tank. It’s like a jungle. HE LOVES it. Every day he wiggles to meet me and have his meal. I even have him eating from my fingers. He blows bubble nests and flares when I show him pictures of himself.

I test his water for Ammo every other day, and for NI and NA every week. I never get a positive reading ever for NI or NA since January 15. I might get .25 Ammo after 5 to 7 days, but generally I am doing 40-60 % water change every 4-6 days.

The water is conditioned and left to sit out for a day or two so it is the same temp as his bowl (no heater, but house and light keep his water right at 70F). If I just clear everything out of the five gallon and place all his plants in there and monitor and test while doing weekly 50% water changes he would be living better and under the same chemical circumstance except with a heater and filter… wouldn’t this be better?

I know the first thing you will mention is that the cycle will still happen, but at what rate? MONTHS? and with testing and maintenance can’t I prevent or push off the cycle, and or intervene to ensure the tank stays safe?

CJ (still Delta’s dad, for now)

Hi again CJ, hopefuly Deltas dad for his natural lifespan!

I’ll reply to both comments here. It will be easier for me to order my thoughts. let me know if anything needs clarification!

I completely get where you are coming from. When things go bad, it’s mostly just waiting around to fix them. I never used to be this calm and patient, but keeping fish has forced me to be this way. cats, dogs hamsters etc. Are all considerably better pets for instant gratification.

I understand it’s disheartening, it’s not just the waiting, but learning from scratch takes a lot of time and effort. You have truly done well to get this far – I’ll bet you know a lot more now than you previously did and it would be a shame for that knowledge to go to waste.

And hey, I’m cool if you do blame me. Sometimes just having someone else to blame makes you feel better, right? I get that. Personally, I’d rather we be friends but I’m still happy to help you out regardless!

It is possible that overdosing with Aqueon water conditioner was responsible for the crash, dosing anything at a 10x concentration in an aquarium is a recipe for disaster. Seachem Prime doses at 1 ml for every 10 gallons, although it can be dosed up to 5x stronger without issues. But even seachem prime at 10x would be problematic it also neutralizes nitrite keeping your fish safe here too (and not affecting the cycle)

If you still have ammonia in the betta bowl then there likely isn’t anywhere for the beneficial bacteria to cling to. When I say the cycle will happen, they still need a home. The filter media (or even a small sponge filter) will rectify this. Without it, it’s possible that your tank will be perpetually uncycled, depending on the environment.

If you do decide to start again on the big tank, I’d personally clean everything. We don’t know what caused the crash. If it’s a residual chemical left over, it could cause issues on the new cycle. While this might not be the case, I wouldn’t want to be waiting around for another 2 weeks if it is. I’d swap out the biorings and give everything else that comes into contact with the water in your tank a good clean. Rinse in freshwater before adding back to your tank.

Hope this helps!

Thanks Ian… No, we are friends, dont worry. Or as much friends can be chating through a blog.

I am going to start over complete tomorrow. I will rinse the tank filter gravel and swap out rings and filter sponge…

Take two.

I will check back in once my ammo declines and NI appear.

Thank you sir and good night,

Thanks CJ,

Haha, well maybe not friends but blog buddies at least 🙂

I have my fingers crossed that this time is the charm. Also, I would advise rinsing the tank itself too – wipe down the glass on the inside of the tank just in case any residue has adhered here. Otherwise this is going to go back into the tank once new water is added.

I’m here if you need any questions or concerns. Good luck!

Hello Mr.Sterling.

Im very new to fish tanks. i recently purchased a 20 gallon tank and i have a sponge filter and a aquaclear hang on back filter.

i set this tank up about a week and like 1 or 2 days and ive done water test everyday but made the rookie mistake and not documenting it all.

but after a week these are my readings and i had 2 of my family members do the same test without my help so i know the test is correct.

ammonia- 0.25ppm
Nitrite- 0.00ppm
Nitrate-20 ppm

I have been reading a lot on this cycle and its almost to good to be true that my tank is cycling this fast. is there anyway i can do a test to know if my tank is cycled? (i don’t mean water test lol) maybe like adding ammonia and seeing if the tank can control it? like i said i’m new to this so i’m not sure.

Hi Wesley,

Truth be told, everyone experiences the cycle at a different speed. I’d keep documenting daily to see what rate it goes down. If you are reading your tests under natural daylight (not indoor lights) and those are your results then I would trust them. I have outlined steps in the guide above, based on following those steps that will let you know if the tank is completely cycled.

Wow, that was quick, Ian, day two and NI ( 0.5 ) and NA ( 5.0 ) are present and Ammo is down to 1.0 from 2.0 in day 2… there were zero readings for everything two hours after introduction of 2.0 ppm ammo.

I rinsed everything thoroughly but, in pre-conditioned water in buckets. I used paper towels to wipe down the entire tank and filter. I changed all filter media as well as used only hands and fingers to scrub decorations in conditioned water. The only thing I am thinking is that after double rinsing gravel from bucket to bucket back to tank in conditioned water, this is where all the bacteria present now were hiding…

Here is to a sped up cycle to continue!

Hi CJ,

Personally, I’m surprised the ammonia has dipped so quickly. The steps you took all sound positive. Let’s hope it’s smooth sailing from here!

Hi, so I posted a while ago asking for advice on my tank. Now, I have been testing my waters every few days and adding in ammonia once it gets to around 0.5. My tank has been for almost 4 weeks now and nitrites still have stayed at 2ppm the whole time and aren’t going down! Did I mess this up again?

Hi Tessa,

It’s hard to say based on the information given. I’d monitor your nitrates over the coming days to see if they are increasing. Make sure you test in natural daylight! If they are at the end of the color chart, a water change or two will get them back down so that you can calculate the rate at which they are rising. If they are rising, then the nitrite eating bacteria are there, just slowly growing. If your ammonia keeps decreasing, then it has to go somewhere. So the first step is finding where that somewhere is.

Tessa, there is a chemical called tetra safestart plus, and another called stress coat plus, what you want to do since you are having a hard time is put some tank water into a bowl and clean your filters using tank water only. Then set the filters aside, drain the tank completely and refill with tap water. use safestart plus which adds the beneficial bacteria to the tank and add stress coat plus as it removed the chloramines to make tap water safe, wait for the temperature to adjust to the temp of the tank your betta is in and add your betta to this tank. Now Test the water in 2 days to look for elevated levels, more than likely they will be very low. At the end of one week regardless do a 10-20% water change and adding stresscoat plus, test it every other day, if any levels get to high do a 10-20% water change, tank should be cycled within a month going this route. Im new, did lots of research and had issues in the beginning but now this method had worked for me very easy and im not scared anymore. Fish need some of those bacterias, dont be affraid of a dirty tank, a clean tank can be much worse for your fish.

Hi Chris,

Given the article is about fishless cycling, a superior method for beginners in that it doesn’t put fish lives at risk, this advice doesn’t ring true.

So glad I found your blog as I’m a complete novice when it comes to fish! I bought a Betta for my granddaughter and picked up a one gallon tank with filter, light but no heater. After doing some reading online, I was convinced that tank was too small and bought a 5 gallon Fluval Spec V plus a heater. Imagine my surprise when after setting up the tank, I couldn’t add my fish without cycling the tank first. I am a bit overwhelmed by the process but your step by step instructions is giving me hope. I didn’t have ammonia but added some food pellets instead as I read you can use food to start the cycle. It’s been a few days and my PH tested at 7.2 and ammonia at 1ppm. Would you advise I use ammonia instead and if so, how much do I add for a 5 gallon tank? Do you have a preferred ammonia source?

In the meantime, my Betta will be stuck in the smaller tank and I’m wondering how often I should do a water change to keep him healthy? Should I test the water first and what level of ammonia would require a change? What % of water change should be done? Should I remove him to do the change or can I do it with him in the tank? I want it to be the least stressful as possible. He is eating a few pellets once per day, I keep the light on for around 10 hours, his fins are open but he does seem to be darting around more. FYI:I use Seachem Prime to condition the water and was told to use 2 drops for my 1 gallon tank. (I used a half mL for the 5 gal tank)

Sorry for all the questions and my ignorance. I never knew keeping a fish could be so complicated. One thing I’ve learned is NEVER go to a chain pet store to buy or be educated about fish!

Hi JJ,

Well done for identifying the need to upgrade, an appropriate sized tank is going to make anything that follows so much easier. Fish pellets, a frozen shrimp or anything else that decomposes can also be used to add ammonia to the tank. My biggest gripe with these is that you cannot add an exact amount of ammonia and record the rate at which it decreases, which makes it easier to chart what is actually happening in your tank. My preferred ammonia is Fritz, however you can use Dr Tims or any other “aquarium ammonia” which allows you to know exactly how much to dose relative to your tank. Alternatively you can grab “pure ammonia” from a hardware store but due diligence is required to ensure it’s free of fragrances and other additives as these can kill a cycle.

As for your Betta, if you don’t plan on keeping him in the smaller tank, then you are essentially performing a fish-in cycle in the small one and a fishless cycle in the large one. I have a guide on performing a fish-in cycle which may be a better option – moving your betta to the larger tank, since he will have to suffer through what is a fish-in cycle regardless if you keep him in his own tank.

You can perform water changes with fish in the tank. The fish-in cycling guide has more information on using water changes relative to chemical build-up.

Don’t worry, we have all been here before. Unfortunately, chain pet stores just don’t train their staff well enough. I highly recommend local fish stores since they themselves are usually heavily involved in the hobby too and give some great advice. Chain stores are a beginner trap, you are not the first and certainly won’t be the last to experience this.

Thank you! I didn’t even think about the fact that I was doing a fish-in cycle in the small tank while doing a fishless cycle in the 5 gal tank to get it ready for my Betta. I moved him into the 5 gal tank after acclimating him to the temp and new water chemistry. The larger tank tested at 0 ppm ammonia at the time I moved him so I will keep testing every day and add the correct dosage of prime based on the ammonia level. Do I add the prime directly into the tank or mix it with water first? Then I keep testing everyday and dose with prime anytime it is over 0 ppm? Once the ammonia reaches 2 ppm, I do a 50% water change with fresh water that has prime in it. Do I also need to add a straight dose of prime even with the water change? Then I keep testing everyday waiting for the ammonia to start dropping at which time I test for nitrites? Then dose accordingly with prime based on the ammonia + nitrite level together. If the combined limit of ammonia & nitrites reach 4 ppm, I need to do another 50% water change, correct? After that keep testing everyday and dose with prime as needed. Is there any point in which too much prime becomes harmful? Once the nitrites start level off or drop, I test for nitrates and hope for my end goal of 0 ammonia & nitrites with what acceptable level for nitrates?

One final question! Would you recommend I add Tetra Safe Start Plus as a safeguard? If so, can I add it directly into the tank when the fish is already in there? And if I go this route, will dosing constantly with prime harm the newly added bacteria?

Sounds like you have your head in the right spot now, JJ!

You have some good questions, let me elaborate:

Prime can be added directly to the tank when being used to “bind” ammonia and nitrite. The only reason you would add it to water prior is if you were using it as a dechlorinator.

Yes, you keep testing every day and react according to the test results (build up happens at different rates in different tanks) and dose with prime accordingly.

Wen doing the water change, you add as much prime to the water being added that is needed to dechlorinate it. Then you add to the tank as much as is needed to bind the 1 ppm. If it makes it easier, think of it as two separate products. One that dechlorinates and another that treats ammonia and nitrite.

Prime is tested safe up to a 5x dose (which would treat 5ppm), which is why I recommend stopping at 4ppm as it leaves a little room for error.

As for the end goal, nitrates will continue to rise until you do a water change. Ideally, you would want to keep these below 10ppm, however, the upper limit for freshwater fish is generally round 40ppm, I have seen many tanks perform just find changing at around 20ppm. Observe your tank and perform water changes accordingly. Generally, you should be able to go a week between water changes in a properly stocked tank.

Depending on who you ask, you’ll get a resounding yes or no on the Tetra Safe Start. I fall into the camp that isn’t convinced by them. Don’t get me wrong, I have seen quick cycles using these bottled bacteria products, but I have also seen incredibly slow ones too. I have seen the exact same without using these bottled bacteria too. The problem is, that these are living organisms inside the bottle. If they are dead, then they won’t do anything to help your tank. The problem is, you don’t know how this beneficial bacteria has been stored or transported, there is plenty of room for it to die. Then you move onto the argument of different brands offering different strains and it all gets really complicated. The long and the short of it is, adding it won’t break your cycle, but you might not see any benefits either. Yes, it can be added with fish and Prime won’t harm the beneficial bacteria.

Hi Ian-

Thanks to your guidance, I think I’ve got this process down. My Betta seems so much “happier” in the larger tank! Tested ammonia today at .25 ppm and added one dose of prime. I’ll just keep going and let you know if I run into any problems. One final question: What do you do when you go on vacation with respect to feeding?

I want you to know how much I appreciate you taking the time to explain the cycle and answer all my questions. I truly believe you saved my Betta!

Hi JJ,

That sounds really positive! Please, if you have any further questions around the cycle, ask away.

Regarding vacations, it depends on the duration. Most fish can handle up to a week without being fed (a hand-delivered meal doesn’t come along every day in the wild)

Longer vacations requires either someone you trust to feed them (pleeeease, measure out each feeding into separate containers, step-in carers are notorious for over feeding)

Otherwise an automatic fish feeder. I have physically reviewed a wide range of them and I can only recommend one, check out the reviews section in this guide if this is the route you take for more pros, cons and how to correctly set them up – it’s a long guide but there is a lot to cover.

Oh, and avoid “vacation feeders” or “Vacation blocks” or whatever they are called. These small slow dissolving cubes or triangles are a quick way to crash your cycle and kill your fish while you are away.

Whatever you choose, a trial run is essential. For example, if you are skipping feeding, skip feeding before you go on vacation and see how your betta handles it. Similarly, set your automatic feeder up prior and observe how it runs – this way you are nearby to fix any problems should they arise.

Hey, thanks for all the great tips! Quick question: Let’s say during the first week my ammonia levels are going up as planned but then my ph drops so I do a 20% water change. Now will the ammonia levels have dropped as well? Do I need to add a little more ammonia? Thanks!

Hi Carley,

Excellent question, a water change will also dilute your ammonia levels and you would re-dose appropriately. Using the test kit after the water change will let you know how much you need to add.

Thanks! I’m also just curious after looking at your chart – does the ammonia stay constant after the first dosing until it begins to drop when the ammo-eating bacteria appears? Your chart shows an increase of ammonia from day 0 to day 10 – was that fish in cycling or were you dosing with a little bit of ammo every day? Should I be increasing my ammo a little bit every day as well?

Hi Carely,

Well spotted, as I discussed with another commenter, this is actually a chart of my last fish-in cycle I performed. I understand it adds confusion, but I thought it would still give a good idea of how the cycle progresses. I couldn’t find the numbers I kept scribbled down on a piece of paper of my last fishless cycle. I should probably make some numbers up to give a better idea than what this chart shows.

You are correct in that the ammonia stays constant until nitrites begin to appear, then it should slowly decrease.

The other thing to keep in mind is that if you perform a water change then this will also dilute the ammonia levels and will need to be redosed.

Kudos to Carly and everybody else that commented.. although you’ve explained it a lot clearer then most sites I’ve been on, it is still way over my head. I don’t understand it at all. I am sure going to need help with this. I had fish for 30 years and never had to go through any of the cycling. I shut down my tank for a couple of years and now I decided to get it up and running again and make a cichlid tank. Ive had cichlids before with no problem, but I’ve never really had any fancy cichlids so I want to make sure I do the right thing. I am going to have a ton of questions so I’m hoping I’ll be able to email you and you’ll be able to reciprocate. Thank you

Hi Sam,

Unfortunately, I don’t give advice outside of these comments. I used to when the site was smaller, but I was soon spending over 4 hours of each day replying to all the questions asked so I had