Last update: November 12, 2022

Ammonia Levels- The Invisible Killer in Your Aquarium

Do you know that you have an invisible assassin in your aquarium?

It hides in every tank and, if left unchecked, will soon kill all your fish.

I’m talking about ammonia Levels in Fish Tank.

And today, I’m going to teach you everything you need to know about it.

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API test solution test tube and color card from ammonia test kit

API AMMONIA 130-Test Kit

  • Lasts up to 130 tests
  • Monitors water quality and prevents invisible water problems
  • Works instantly to make aquarium water safe for fish
Seachem prime best concentrated water conditioner for marine and freshwater

Seachem Prime Fresh and Saltwater Conditioner

  • For both freshwater and saltwater fish tanks
  • Removes chlorine and chloramine
  • Effectively detoxifies ammonia, nitrite, and heavy metals
Api ammo chips ammonia removing filter media

API AMMO-CHIPS Filtration media

  • Removes toxic aquarium ammonia
  • Works continuously to remove deadly ammonia
  • For use in any aquarium filter

What are ammonia Levels, and where does it come from?

Ammonia, NH3, is an invisible chemical that is highly toxic to your fish. Unfortunately, it also occurs naturally in every aquarium

As organic waste begins to break down, it releases ammonia.

These unnecessary waste include:

  • Fish breathing
  • Fish waste
  • Uneaten fish food
  • Dead pieces of aquarium plants
  • Decaying algae
  • Dirty filter pads

The only way to avoid ammonia is to not own a fish tank.

Fortunately, in a healthy aquarium, nature takes care of ammonia for you.

Do you remember when you cycled your new aquarium?

Well, that was done to introduce beneficial bacteria into your aquarium – bacteria that eats ammonia.

This process forms part of the nitrogen cycle.

Don’t remember how the nitrogen cycle works? Here’s a quick recap…

Waste breaking down into ammonia nitrite and nitrate in aquarium diagram

1. As waste breaks down, it produces ammonia.

2. Good bacteria, called nitrosomonas, break down the ammonia into nitrites.

3. A second bacteria, called nitrobacter, then feeds on the nitrites and produces nitrates.

Nitrate levels are then removed from your aquarium each time you perform a water change.

In high enough numbers, these beneficial bacteria break down ammonia as quickly as it is produced, keeping your tank ammonia free.

What ammonia levels are acceptable in your aquarium?

The acceptable level of ammonia in your mature tank is…


Yep, you read that right…

Ammonia is pretty bad news. In a stocked tank, your aquarium test kit reading for ammonia should read 0 ppm (parts per million).[1]

If ammonia levels are higher than zero, you need to find the cause of the problem, and fast. The lives of your fish depend on it!

There is only one exception to this rule…

When you are cycling a new aquarium.

You see, in a new healthy tank, bacteria does not exist in large enough numbers to break down the ammonia as it is produced.

This is actually a major reason why you cycle – to allow bacteria that live in your biological filter to grow in number until they can break down ammonia as quickly as it is produced.

So, if you are cycling a new fish tank, high levels of ammonia are to be expected. But in an established aquarium, a spike in ammonia can indicate major problems.

What happens if your ammonia levels are too high?

Once your ammonia levels exceed zero, that’s when problems start to occur.

At low levels, ammonia burns the gills of your fish, placing them under incredible stress.

As ammonia levels rise, it damages the brain and organs of your fish, until they eventually die.

This process is known as nitrate poisoning. And, what a horrible way to go!

Some fish have a higher tolerance to ammonia than others.

If your fish can tolerate elevated ammonia levels, it doesn’t mean that she is happy. Your fish are likely under immense stress.

When fish are stressed, they are more likely to develop diseases, lose their color, suffer from stunted growth or even become unable to reproduce.[1]

It’s simple… Keep your ammonia levels at zero for happy and healthy fish.

What causes high ammonia levels?

If you can associate any of the following with your aquarium…

  • Too many fish – overstocked
  • Overfeeding
  • Weak filtration
  • No nitrifying bacteria in your filter
  • Not performing regular maintenance

Then, your tank is at risk of elevated ammonia levels.

FishLab Fact: A sudden jump in ammonia levels is called an ammonia spike.

How do you test for ammonia?

Unfortunately, detecting high levels of ammonia can be difficult because it’s invisible. And by the time you notice the effects of ammonia poisoning on your tropical fish, it’s often too late.

That’s why it’s important to regularly test your aquarium for ammonia.

And by far, the most popular way to do that is with an aquarium test kit…

API test solution, test tube and color card from ammonia test kit

Lasts up to 130 tests

If you walk into your local fish store, chances are that this is the test kit you will find on the shelf….

And that’s not a bad thing. API ammonia test kits are cheap and work well enough, allowing you to confidently determine if your ammonia levels are higher than zero.

If you already purchased an API Master Test Kit, this test is included in the box. If you don’t have one of these, go out and buy one now! Not only does it test for ammonia but also pH, nitrites and nitrates. These test kits cost much less than buying each one separately.

Best of all, these test kits are simple to use. Simply add some aquarium water to the test tube and a few drops of the testing solution, then shake. Once the fresh water changes color, match it to your color card to determine your ammonia level.

Pretty simply, huh?

Test strips are another product you can use to determine the ammonia levels in your aquarium. But don’t expect any degree of accuracy. If you want to use test strips, I recommend confirming the results with a test kit before taking any action.

Check out my test strip guide for more reasons why I don’t recommend test strips.

How do you reduce ammonia levels?

Just used a test kit and discovered that the ammonia levels in your tank are dangerously high?

Don’t panic!

I’m going to walk you through everything you need to do in the event of an ammonia spike.

1. Water change!

The first thing you want to do is perform a water change of at least 50%.

What you are doing is swapping out ammonia-filled water for water that is ammonia-free.

By performing a dirty water change, you are effectively diluting the amount of ammonia that has built up in your aquarium.

2. Add cycled filters

As I touched on earlier, two different types of good bacteria turn ammonia into nitrates, which are relatively harmless to your fish.

In large enough numbers, these bacteria eat ammonia as quickly as it is produced.

And, these bacteria just happen to live in your aquarium filter.

By adding another cycled filter to your aquarium, the bacteria will eat the ammonia, lowering the levels back to zero.

But if you don’t have multiple tanks, tracking down a cycled gravel filter can be difficult. If you have a good relationship with your local fish store, or a good friend in the hobby, they may allow you to take one.

FishLab Tip: Adding a sponge filter is a great way to have a second cycled filter on hand when you need it most – allowing you to quickly set up hospital tanks or for use in emergency situations such as an ammonia spike.

3. Water conditioner

In an ammonia emergency, water conditioner can be used to render ammonia harmless.

By binding the ammonia, the water conditioner gives your bacteria the opportunity to catch up.

And when it comes to water conditioners, it’s no secret that Seachem Prime is one of the best on the market…

Seachem Prime best concentrated water conditioner for marine and freshwater tanks

Not only does it detoxify ammonia, but it also deals with nearly any other water quality issue that may arise![2]

I highly recommend keeping a bottle on hand, just in case of an emergency.

And trust me, an ammonia spike is definitely an emergency.

You should note that water conditioners only bind ammonia for up to 48 hours, after which they will be released…

So, you need to find the cause of your ammonia outbreak fast, otherwise you must continuously add water conditioner to your aquarium.

4. Ammonia Levels – removing filter media

Is fixing the cause of your ammonia issue going to take some time?

You can also add media to your filter that is specifically designed to remove ammonia from your aquarium.

One popular product is…

API Ammo-Chips ammonia-removing filter media

API Ammo – Chips…

Simply add the Ammo-Chips to your filter (don’t forget a filter bag) and sit back as it removes ammonia from your water – like magic!

How does it work?

Ammo-Chips is a branded name for zeolite, which is a mineral that naturally draws ammonia from water without any side effects.

However, zeolite is not a “set and forget” solution to your ammonia problems…

Just like activated carbon, it will keep absorbing until it is “full.” When this happens, zeolite will not remove any more ammonia from your aquarium.

In cases of extreme ammonia levels, zeolite might not even last two weeks. But it can always be replaced with a fresh batch.

Before I move on…

All these solutions can be used effectively to lower the ammonia levels in your tank. But…

These are only temporary solutions.

You see, while these may fix your ammonia problem, they do not solve the cause.

And that should be your primary goal – finding the cause of your high ammonia levels. After all, in a healthy and balanced tank, your ammonia levels should be zero without any extra help from you.

These treatments are best used to buy your tank some more time – they prevent any ammonia from harming your fish until you deal with the cause.

How do you prevent an ammonia spike?

Remember how I listed the common causes for ammonia spikes earlier in this guide?

Well, prevention is as simple as making sure each cause is kept in check.

Below, I cover how to prevent your ammonia levels from rising in more detail…

1. Double check how many fish are in your aquarium

How much room does a fish need? Likely more than you think. Even a single betta needs at least a 5-gallon tank to be truly happy and healthy.

Overstocking your fish tank can lead to ammonia problems. Too many fish eating and pooping in a tank that is too small can quickly lead to an ammonia spike.

Keeping too many fish is a particular problem among beginners who do not know better.

If you are still deciding which fish to keep in your tank, speak to someone experienced. There are numerous online forums where experts happily advise on suitable fish for your aquarium.

2. Overfeeding

Overfeeding can also be responsible for raising ammonia levels.

Okay, so you have the best of intentions, ensuring your fish don’t go hungry. But any uneaten food will begin to rot and as it breaks down it will release, you guessed it… Ammonia!

So, take your time and figure out how much food your fish need.

The right amount of food entirely depends on the type of food and the species of fish you keep in your tank.

3. Perform regular maintenance

We all know we should perform regular maintenance on our tanks.

Water changes, using a good gravel vac and cleaning the filter are all essential steps to keeping a fish tank in good working order.

But sometimes, life gets in the way. You miss a week. Then another. And before you know it, all that uneaten fish food and poop is breaking down into ammonia.

You would be amazed at just how many aquarium problems can be solved simply by sticking to a regular maintenance schedule. Make a routine and stick to it – the lives of your fish are at stake!

4. Don’t kill your beneficial bacteria!

You know the good bacteria in your filter? Well, if they die, you will soon experience an ammonia spike.

Without the bacteria to eat the ammonia, it is free to increase to alarming levels.

I know you would never intentionally kill off your biological filter, but I have seen many beginners rinse their filter in tap water because they don’t know any better. That chlorine will kill your filter bacteria quickly.

Also, make sure you carefully follow the instructions when adding any chemical, such as medication, to your aquarium – this too can kill off filter bacteria.


While ammonia is certainly deadly, it isn’t something to be feared.

In a healthy, balanced aquarium the good bacteria eat it as quickly as it’s produced.

And in the event of an ammonia spike, there are many different solutions for lowering your ammonia levels while you look for the cause of the problem.

How do you deal with an ammonia spike? 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 (45)

Ok about a month ago I accidentally put new filter in but forgot to condition the water so it sat for about 10 mins before I realized what I did so I took it out and rinced it with conditioned water is the filter bad now ? I’ve been noticing the ammonia levels in water have been high and won’t go down is the filter the problem ?

Hi Donny,

If you have replaced your filter with a new one, then it’s possible that there isn’t enough beneficial bacteria to process your ammonia – a new filter won’t have any beneficial bacteria present. Alternatively, if you added chlorinated water to your tank, which is what I believe you are saying, you will may have killed your beneficial bacteria. In either case, you may have to cycle your aquarium all over again to encourage this good bacteria to grow.

My tank is now 2 months old never had ammonia until now. My levels in my tank have always been spot on including zero ammonia got my water tested today and I had a reading of 1.5 on the ammonia scale any ideas on what the cause is? And how to I stop it from progressing further?

Hi Lee,

If it’s not a build up of waste (overfeeding, overstocked, non-maintenance etc.) then it’s possible that the good bacteria in your filter have died.

My tap water tests positive for ammonia at .25ppm. My fish are stressed due to ammonia level in the tank of .50. Its a new tank and I did a start using the Tera safe start method. My ph is 6.6 and the nitrate and nitrite levels are ok. I don’t know what to do. I have lost 6 Barbs and my other fish are not eating.

Hi Jeff,

Unfortunately, tetra safe start isn’t a substitute for cycling your tank.

Don’t worry, plenty of us have been there before. You just need to cycle your aquarium. While I cannot guarantee that you will won’t lose any more fish, it will give you the best chance of saving them.

Check out my fish-in cycle guide for more details.

I have a 30 gallon tank with 5 goldfish. They were previously in a 10 gallon tank but just put them in the 30 a few days ago because they are now each roughly 2.5 inches long. However, the water has almost always been murky with them, with the exception of about 2 days after water changes. What can I do to keep the water from getting murky and cloudy?

Hi Tony,

Wow, 10 gallons for 5 gold fish is seriously overstocked. Even in a 30 gallon, there are plenty of fish keepers who would be wary of keeping 5, especially if they are common. I’d start by checking your water parameters with a good aquarium test kit, to ensure everything looks normal. If anything looks odd, you will need to get to the bottom of it. When you are heavily stocked, frequent maintenance is key, such as using a good gravel vacuum to suck up the gunk at the bottom of your tank and performing regular water changes. If everything looks fine here, check out our guide to getting rid of cloudy water, it outlines all the common causes of cloudiness that would otherwise arise in a healthy tank.

A new tank that is actively cycling can make the water cloudy for a few days, especially if you added bacteria to start the cycle.
I would add Seachem Purigen into the filter. It’s an excellent media that helps clear up murky water rapidly. It acts much like charcoal. In fact, I’ve replaced my charcoal with Purigen and never looked back. 🙂

Hi Robert,

Do you mean ammonia? Snails eat, poop and when they die, their bodies rot. All of these things give off ammonia.

If you are referring to the beneficial bacteria, then snails won’t directly harm it and the ammonia they produce will contribute to the bacteria forming during the cycling process.

I have a brand new 30 gallon aquarium that I recently filled with distilled water carefully adding the required minerals. I had to use distilled water because our city water changed from using Chlorine to Chlorine with Ammonia added. Residents established tanks were killing fish and potted plants and flowers were dropping dead due to this change. There is nothing in this tank besides numerous plants. I checked the Ammonia level this morning and it is above 4 ppm. How can that be? Does distilled water contain Ammonia?

Hi Frank,
I would be surprised if the distilled water was the source of ammonia, although it wouldn’t hurt to test it with an aquarium test kit just to make sure.

Based off the information provided, it’s possible that your plants are they cause. Your plants will also give off ammonia as they break down – small leaves and other pieces being shed here and there might be almost unnoticeable, but may be decaying and giving off ammonia.

Also, when water supplies add ammonia, it combines with chlorine to form chloramine. Water conditioners like Seachem prime should be able to deal with this chemical.

Checked the ammonia level right out of the distilled water bottle and it 1.00 ppm. I was of the belief that distilled water had zero ammonia. I think that level of ammonia and the decaying plants may be contributing to my overall ammonia level.

I have very little experience with using distilled water but my understanding was the same, it should be ammonia free. I’ll bring this up at my next meeting at my local fish club, I would be curious to know if this is an anomaly or expected. I am also curious if it is ammonium you are detecting (depending on the pH of the distilled water) – very few aquarium test kits can tell the difference and lump them together in a single reading.

I recommend creating a free account on a online aquarium forum and asking there, it is highly likely others using distilled water will have the experience to answer your question.

One last aside, is your tank cycled? Even though you only have plants in your tank, if you cycle your aquarium it should help keep ammonia low levels low and help balance out your ecosystem – a cycled tank can grow enough bacteria to easily handle 1 ppm of ammonia as quickly as it is produced.

I’ve had my aquarium (75g) set up for over 2 years now.. Up until about three weeks ago, I was getting a ZERO reading on my ammonia test kit. Recently I had decided to swap out the fish I was keeping in those past years for something different.. South American Cichlids. One of which is a Tiger Oscar. A very messy eater to say the least. The mess that he rejects through his gills makes an awful cloud of un eaten food. This only applies to the pellet king of food and a very little amount (…If none) when eating a super/meal worm. Eating frozen brine shrimp, blood worms and other types of frozen “fall apart” foods are also messy but nothing as bad as pellet sticks…What a mess! The substrate I have is sand and just recently, was anywhere from 1 – 3 inches deep. An ammonia and nitrite home for sure!
Back to my issue… Since I have removed 98% of the substrate and put my plants in clay pots sitting in the aquarium, I get ammonia levels steady at 1.0 ppm
My water changes consist of 15 gal. of water and a filter media cleaning. (done in discarded aquarium water)
My water I use is RO water. I have been using this type of water for over 2 years up until I learnt that its pH below 6.0 and does not measure on the colour scale. This makes me believe that the water is severely acidic. Being acidic as the chart suggests tells me that perhaps the leafs on my live plants are being eroded hence causing ammonia in the water and a never ending battle with ammonia.

Hi Will,

Swapping over to new fish is fun! It’s a shame it can come with a whole bunch of headaches like the ones you have mentioned.

Further to this, the ammonia eating bacteria that live in your filter dislike acidic water. If your water was acidic enough, you may have killed them off, which would cause the constant ammonia – your tank will need to go through a cycle again.

Also, are you rinsing your biomedia that often too? Or only the mechanical filtration? I only ask because rinsing biomedia this often is unnecessary and may have contributed to the problem.

Hi Ian.
So glad I found this article! I have had my mixed small fish community 240L for 3 years now & yes, I am going to admit it is slightly over stocked, as I have moved fish about from my other 5 tanks. I do perform very strict maintenance schedules, water changes every week (30%). It has a cannister filter (EFX 300 which is pretty much like Fluval 306). I have sand substrate & only plastic plants. Anyway, to the problem which is that about 14 days ago I spotted anchor worm on some fish. It was not practical to net the fish and manually remove, so I treated with a Waterlife treatment as per instructions & it cleared up the problem pretty quick. Then after day 5 of treating, I noticed a harsh spike in ammonia to 1ppm (this medication is said to be filter friendly & btw is the only medication I have ever used in this aquarium). I didn’t panic, performed more water changes hoping things would catch up, then 5 days ago the entire filter crashed, with ammonia levels going up to 8+ppm (using API test kits). I immediately hooked up a filter (Fluval FX4 which I know is over kill for a 60 gallon tank, but it was all I had) combined with daily 50% – 60% water changes Anyway, basically I still cannot get the ammonia down even using zeolite & Ammo Lock which converts the ammonia to ammonium & lowers the ph to below 7. I added more air stones, placed some of the EFX 300 media in the FX4, loaded the EFX up with zeolite as well.
My questions are, can you use too much zeolite? (I currently have 3 kgs in the EFX filter & although well rinsed, the water has gone milky cloudy) & secondly, do I just keep doing large water changes or stop & leave the Ammo Lock to keep the ammonia as ammonium until the filter/s catch up?
Remarkably I have not lost any fish yet!
Thank you for reading, I look forward to your reply.
(PS: If you are wondering why I have not moved the fish to other tanks, it is because they now contain puffers & the water in them is brackish).

Hi Steve,

What a terrible predicament to find yourself in. I’m sorry to hear it.

Since you use Waterlife, I assume you are from Europe/UK, it’s not a product that is readily available here. Unfortunately, I cannot comment on it as they cause as I have no experience with it.

How do you know you have not gotten the ammonia down – are you using a dedicated ammonia test kit? Test kits like API will still show ammonia when a water conditioner like prime is used to convert it to ammonium. This can often lead to people acting what is essentially a false positive. It’s entirely possible your ammonia is down. Seachem makes an ammonia test that is capable of testing for both, it might be worth checking out to see exactly what is happening in your tank.

Just a follow up on your PS, I just want to confirm that this tank that isn’t brackish – You are probably all over this but salt can cause zeolite to release ammonia.

Large water changes and ammo lock will work as long as your beneficial bacteria isn’t dead. Are your nitrates still raising? Or are you experiencing a nitrite spike too? It’s hard to say the state of your beneficial bacteria without testing. If it’s there, it will eventually catch up. But if it’s completely nuked, you’ll have to treat this as a fish-in cycle from the start. I really hope this isn’t the case for you though.

As for using too much, the only issue here is that if your beneficial bacteria have completely died, and your tank needs to re-cycle – use of zeolite can cause the cycle to stall, as it removes all the ammonia the first bacteria needs to establish itself.

What about PH levels? I’ve read that ammonia levels are only toxic if PH levels are high.

I have a 55 gallon tank with a constant ammonia reading of 3 or 4.

The article below says: “Any pH reading of 7.2 and below will not have a problem with ammonia toxicity up to 7.3 mg/L total ammonia compounds or less.”

I have a lower PH, so according to the article, I’m good, and my fish seem fine. What are your thoughts?

Hi Don,

As this article is aimed at beginners, I tried not to complicate the topic by introducing ammonium as a variable. You are correct, Ammonia can be less of a concern when pH is factored in.

If I’m understanding you correctly,Your example is 7.3 ppm of Total ammonia at a pH of 7.2? Correct me if I’m wrong here, but doesn’t sound quite right. If my maths are sound, 78F at total 7.2 be over 0.05 ammonia, which would be toxic to fish. Temperature also plays a slight role in total ammonia toxicity too.

Assuming your fish can actually thrive in low pH water, there is certainly less need to worry about ammonia. You can use seachems ammonia test kit to double check – it independently tests NH3 and NH4, instead of total ammonia like most test kits.

. I just up graded my filter to a fluval FX 4. For my 125 Gallon Tank. It came with a carbon pad? Is this doing anything ? My amonia is about .5 should I add more carbon. Did a huge water change just today I’m hoping tomorrow it may be better. What do you think

Hi Kenny,

You are using the wrong tool for the job. Activated carbon doesn’t remove chemicals like ammonia from the water. See my activated carbon guide for more info. It doesn’t do much to protect your tank from an ammonia spike. If you swapped out your filter, it’s possible you removed your beneficial bacteria that was in the old one and crashed your cycle. If this is the case, you will need to start the cycling process from the beginning.

Hi Ian,
I see sudden spike in ammonia in my Tank, not over stocked , water change every 2 weeks 40%, planted aquarium trimming leaves often, after noticing ammonia of abt 1.5, changed water twice 50% alternate day, added zeolite in filter, added air stone for more air circulation, by doing all this amonia level decreased to 0.5 but not able eliminate. i have 4 medium size angle fish of 4-5 inch size, two guppies, one pelecos , its well cycled aqauarium with no history of amonia for past one year. please suggest how i can fix issue, is there way to increase the benificial bacteria in tank? i even vacuumed the gravel and its clean.

Hi Senthil,

If your ammonia is not decreasing, it’s possible the tank cycle has crashed and you will have to start over with a fish-in cycle. What the exact cause of this would have been, I cannot say, but common causes include rinsing the aquarium filter with chlorinated water or disposing of the biofilter.

Hi Sam,

Great question! Ammo Chips and any other ammonia absorbing chemical media, like Zeolite, can slow or even stall the nitrogen cycle. If you are cycling, it’s best to leave these out. A properly cycled tank that is correctly stocked and maintained shouldn’t need ammonia removing media anyway.

I have a 10 gallon tank, I’m new to this wonderful hobby. The question I have is would running two filters at the same time swapping filter media at alternate times be a solution to keeping bacteria in the filter media at all times. To keep ammonia levels to zero.

Hi Tom,

Welcome to the hobby! You chose a great size tank to get started with – it’s not too small, which will make your life considerably easier.

Excellent question, this is actually a common set up. You would use ceramic noodles as a home for the beneficial bacteria, while the sponge filters out the free floating gunk. This way, you can dispose of your sponge as often as you won’t and it won’t affect the balance of the tank. Many “disposable cartridge filters” don’t have enough room for both ceramic rings and sponge so be careful here. If you are in the US, the AquaClear HOB filter is a great beginner filter for mixing various types of filter media.

Help I’m starting a 10 gallon tank & a 20 gallon tank no fish yet. My ammonia level is really high should I just leave it & let it cycle or can I add something

My grand daughter has a Betta tank and has been losing Betta quickly. They just bought a new larger tank with filter, all new plants, and new gravel. Set it up Sunday and the fish was dead last nigh(Tuesday). I tested the water and here are the results
KH…,……. …180
General Hardness. 180
Ammonia. 0.25

I know 3 are in the caution range but didn’t know if it was enough to kill the fish

Her brother has the same tank as her first tank where her fish kept dying and his is perfectly fine and we do everything the exact same

Any suggestions are appreciated. Thank you

Hi Denise, did you cycle your tank? It sounds like your tank isn’t cycled.

A properly cycled tank will read:

Ammonia: 0
Nitrite: 0
Nitrate a readable number, forever increasing (you get this back down with the weekly water change)

I have 4 fish tanks, 3-29 gallon and 1-5 gallon. All were very well cycled with ammonia before any fish were added. After about 5-7 doses of Ammonia the tanks would immediately read 0 ammonia and 0 nitrites. If it did that 2-3 days in a row I considered the tank cycled. The entire process took 4-6 weeks.

Then I added fish. Now my ammonia readings on 2 of my tanks is 8.0 ALL THE TIME, Nitrites are at zero or at .25. Nitrates are also low. The other two tanks always have ammonia readings of .50 to 1.0 ppm.

To keep the Ammonia deactivated I add Prime daily and sometimes AmGuard. The Ammonia readings stay the same.

I bought a kit to show if my readings were for Ammonia or ammonium – and all my tanks tested zero Ammonia – it’s all ammonium. I assume that is because I constantly add Prime and AmGuard. This test is rather tedious and I would rather NOT do it daily – so I just assume none of the tanks showing ammonia are actually showing ammonium.

So at what point will my “false” ammonia readings of 8.0 go down to zero with the API kit? Is it because it’s not converting to Nitrites very well? Does Ammonium convert to nitrites with the filter bacteria? Is there anything I can do to “wipe the slate” to where my API test kit shows actual ammonia again and not just ammonium?

I do weekly water changes of 50-75% each week (with an occasional going 10 days before I get to it). I add Prime of course to remove the chlorine. The only thing that changes is my PH. Ammonia levels never change. I do have a bad habit of overfeeding – I have some fish that eat nothing but pellets and may take an hour to eat just one. I also have other fish that only eat at night so I have to make sure there is enough food leftover for them to eat. If there is a bunch of food left in the morning I use my gravel cleaner to remove it.

I don’t know for sure if I’m overstocked. I have one tank with 6 LARGE Gourami’s (all semi-aggressive) and when I had 3 more Peaceful Gourami’s in there with them my water was always cloudy – as soon as I removed the 3 peaceful Gourami’s I rarely have trouble with cloudiness. My other 2 29 gallon tanks have about 30 fish in them with sizes ranging from about 1/2 inch to 5 inches. I rarely have issues with cloudiness unless I wait longer than 10 days for a large water change or fail to clean up the excess food as necessary. One tank also has a serious snail problem but I have two snail eating fish. I’m still removing well over 100 snails per day from the tank. My 5 gallon tank has 5 Rasbora’s (very small fish) yet it is one of them showing 8.0 levels of Ammonia and never more than .25 Nitrites. Water is crystal clear and I am not overfeeding,

Our city’s average PH is 9.4 – my tropical fish need it to be more in the range of 6.8-7.2. KH is 5.3 and GH is 10.6. After every water change my PH jumps to the highest level the API kit measures – 8.9. I use PH down to get it as close to 7.0 as possible. Of course I have a rebound due to KH and sometimes have to add more PH down. I try to do this in small doses over a period of 2-3 days. I’ve never killed a fish due to PH changes as far as I know. Also, our city – like everybody else’s, uses Ammonia to adjust the chlorine in the tap water and make it more palatable – problem is there is always leftover Ammonia in the tap water of about 1.5 ppm. So with each water change I’m adding small amounts of Ammonia (I’ve talked to the city water manager and he said the ammonia readings should be zero if they are using the correct amount of ammonia and he said he would look into it – that was 3 weeks ago so I’ll need to call him again.)

So I guess my question is what do I do about the ammonium vs ammonia issue or do I always have to run the test that shows if the 8.0 ammonia is actually ammonium? Is this a Nitrite issue and why are my tediously cycled tanks not converting the ammonium to nitrites?

My other question is your thoughts on adding PH down after every water change. I don’t know what else to do – if I don’t do something to bring the PH down then my fish will die – a-9 PH is not acceptable. I get a lot of flack on fish forums for adding PHdown like I should be doing it “naturally” but my opinion is that I have more precise control of dosing with the chemical than I do with any organic remedies.

Thanks for your help – Jan

Hi Jan,

That’s an interesting scenario. The appearance of nitrite in these two tanks indicates that something has occurred that has crashed the cycle.

Ammonia bound by prime (ammonium) will eventually become cycled in the same way. This is largely how a fish-in cycle would work if using the seachem prime method and dosing daily. This method, while slow since it has to be done with water changes (1 ppm of prime will only treat 1 ppm combined of ammonia + nitrite) but it will eventually get there. Longest fish-in cycle I have personally seen took 6 months, but I have never seen anything else come close to that. Before 4 months was the longest I had seen.

For the snail problem, assassin snails work exceptionally well. I know it sounds weird, but fight snails with snails is actually a good solution to a snail infestation.

9.4 for average tap water? That’s astronomically high. Are you sure that’s right? That would be like drinking water with a spoonful of baking soda. Judging by the ammonia present at the tap, it sounds like there are some problems here. Unfortunately, this is what you have to work with. I have read of people in india working with worse, so it’s definitely possible but it requires extra input on your part.

I’m on your side with using chemicals. Especially with the quality of water you are using. IF you are keeping neutral pH loving fish, that is far too high. I share your feelings on the chemicals being able to be precisely added. Organic remedies, while they may work well for some, are a balancing act, if they work at all. If you are going to be adding a pH down product during a water change, look into Seachem Neutral Regulator. It adjusts pH to 0, removes chlorine (or in your case chloramine) and detoxifies ammonia. You might find it easier than dosing with prime + ph down.

Hello Ian,

Thank you for all your help and knowledge while I began this hobby in January. January 15, 2020 is, Delta, my son’s fish’s one year anniversary with our family. Boy has he grown since. He is a real beautiful fish and has grown to have a central part in our family. Now everyone feeds him and he recognizes my son, wife and me and comes to greet us as we say hello.

Now, why am I writing? I have an ammonia problem with my new water supply. I recently moved states, yes he managed to survive an hour and a half car ride, and the water quality in our new place is much different. It appears the water out of the tap has a .5 to 1.0 ppm content. Do you have any suggestions on how to rid my water of ammonia?

I have already completed a few water changes with this water. I have tested the tank and ammonia never seems to rise above .25 ppm and then lowers as the water circulates between changes. All the live plants in his tank are helping.

I only now am concerned as I am planning a move of Delta into a new 20 gallon long. It is cycling now and everything seems fine. My main concern is when I have to do water changes in this new tank even using aged conditioned tap water I am going to be introducing larger quantities of ammonia. I am not adverse to buy bottled water, but I am looking for other thinking to solve this problem. I don’t want to resort to using prime as a daily or every other day crutch for unhealthy water.

Thank you, I hope you and yours are well.

Hi again D.D.

I hope you have been well! This is a common problem in certain locations in the US. Fortunately, it’s easily fixed, as long as your tank is properly cycled. Seachem Prime will lock up ammonia for up to 48 hours. In this time, the ammonia should be broken down by the beneficial bacteria and rendered harmless. A little bit goes a really long way, which is what makes it my favorite and what I personally use.

If you are still reading ammonia after this period then it’s possible your tank cycle has stalled (which would follow with a spike in nitrites) or it’s “ammonium” which is harmless but a whole other chemical to test for, but it’s harmless. At the time of writing this, only seachems ammonia kit can tell the two apart (ammonium/ammonia), the other kits read both as ammonia. However, one step at a time, it will be easiest if your tank just cycles the recorded level of ammonia in 48 hours while the seachem prime keeps your fish safe.

Thank you Ian, I am still new at this and this helps me feel better. The 20 gallon is still cycling. I did think this would naturally take care of itself. But, if after going through all this and then the family pet doesn’t make it through this transplant that would be horrendous.

SO, I did get some prime and now I add it to Delta’s water changes in his 5 gallon. And, I do test his water after every change now. I have noticed it doesn’t take longer than a day even if I do greater than a 50% change for ammonia to read zero.

Once D is comfortable in his new tank, we are going to get a second Betta.

Thank you Sir, I hope you and yours enjoy the holidays.

Hi D.D,

That’s awesome that it was an easy fix. It sounds like everything is ub order since the ammonia is going down under a day, which is no doubt reassuring. Unfortunately, you’ll need to use seachem prime each and every water change now. However, if that is your primary water conditioner then it doesn’t really add an extra step.

Ooooh, a second fish? How exciting. Be careful, that’s how my life-long obsession started.

Wishing you a merry festive season!

which test kit is it. The ammonia in my tank reads 0.2ppm and I need to measre ammonia not ammonium. I added prime and ammo-lock

Hi Tom,

If I understand what you are asking correctly, dosing to a standard API ammonia test kit should work just fine for most circumstances including yours.

What species of fish do you have? Also, what size aquarium was it in?
These are really important questions because certain fish produce more ammonia than others. in aquariums 100-120 gallons or less, Goldfish and Koi will produce ammonia at levels that are more tedious to deal with, they aren’t the only fish that produce ammonia in far greater amounts than most fish though. Also, one of the most common mistakes in the aquarium hobby is that people buy aquariums under 50 gallons for their first aquarium, it may be cheaper to get a small one, but remember: the smaller the aquarium, the more maintenance it will need. So unless your an expert, I wouldn’t dare start a tank smaller than 50 gallon. start with a 75 gallon instead, also start with hardier fish like some corydoras catfish and a clown pleco (they’re one of the smaller species and only get about “3 1/2” inches max. 3-5 ghost shrimp would be good too (they are sold for $1-2 per 10 of them at most “Pet Supermarkets”). otocinclus catfish are a good replacement are a good replacement for plecos as they get a little over an inch long but you’ll need 4-10 of these so i’d just get the clown pleco instead, if you can afford it, i’d suggest getting 1 orange mexican crayfish, they are territorial to each other but typically leave other fish alone, also not only are they small but they’re active a lot more than the larger, destructive species that like to dig.

Hi Tom,

You are asking what type of Zeolite is more effective and better? While it is possible is variation in performance, any of these products should be effective at removing ammonia given it is essentially the same thing with different branding.

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