Last update: March 20, 2024

Cloudy Water in Aquarium – How to Fix Your Hazy Aquarium

Are you staring at your cloudy fish tank in disgust?

It doesn’t have to be this way!

Today, I am going to take you through the common causes of cloudy water and how to get rid of cloudy fish tank for good.

Every fish lover and hobbyist has gone through the dreadful episode of encountering cloudy water.

Apart from having an uninviting look, these gray aquarium tanks can pose various threats to the fish and the aquatic microclimate in your aquarium.

If you wish to see your fish healthy and thriving, we recommend paying close attention to your cloudy water issue and solving it as soon as possible.

But first, take a closer look at that fog in your tank and tell me what color it is…

NOTE: Consider filling a clear glass mug with the tank’s water to inspect the correct color and find the reason corresponding to it. Also, these handy aquarium essentials will help fix cloudy and toxic water :

White cloudy water in aquarium

If your mug showcases milky white water, then chances are you are either dealing with bacterial bloom or unwashed substrate.

Your water can also have a few visible particles if it turns wholly or partially opaque.

Sometimes, you can barely see it, a slight grayish haze…

Aquarium with white haze in water

Other times, it looks more like milk than water.

Thick white cloudy aquarium water

Seriously, there are fish in there… Somewhere.

Here are the reasons why your aquarium looks like it has been blanketed in white fog…

1. Unwashed substrate

Every aquarium needs a colorful substrate batch to add vibrancy to the tank; however, you will soon notice cloudy white water if the new set is unwashed.

Adding new gravel creates residue or specks of dirt, making the water whiteish murky in color. If your substrate is extremely dirty, the tank can also showcase a gray tone instead of a white.

Moreover, hobbyists should never forget that large pebbles do not make excellent substrates for your fish tank. The food you feed often gets lodged between these pebbles, and your fishes cannot reach such cramped spots.

This uneaten lodged food eventually produces DOCs or dissolved organic compounds in your aquarium.

Did you forget to wash your substrate before adding it to your established aquarium?

If the partial water turns cloudy within couple hours of setting up your aquarium, then this is probably why.

You see, gravel and sand substrates contain really fine specks – created when it rubs together…

Now, these dust-like pieces are so small that you won’t even notice them at first. However, when added to green water, they separate from the larger pieces of substrate and float around your mature aquarium.

The result?

A very visible and ugly haze.

I know it’s too late now, but this is why you should wash sand and gravel substrates before adding them to your aquarium – it removes the fine dust.


  • The leading cause of cloudy white water is unwashed substrate or residue from gravels, rocks, and other substrates.

Monitor your tank’s pH, Chlorine, General Hardness, Carbonate Hardness, Nitrate, Nitrite, and Temperature for a safe habitat with this test kit:

Most Complete Aquarium Test Kit

How to get rid of it!

To get rid of the cloudy water, you can try a few solutions. A quick fix is to change your water entirely, so all the floating particles and little dirt pieces get removed from your tank.

The next step is to take out your gravel and clean it thoroughly. We highly recommend giving your new substrates a complete thorough rinse before introducing them to your aquarium.

If your aquarium has a water filter cartridge with a fine mechanical medium like filter floss, you can avoid changing the water. The filter floss will easily trap all the dust floating in your tank, resulting in a clean tank with clear water. Hobbyists can also take the help of any water clarifier to accelerate the cleaning process.

If you can see a thin layer of dust accumulated on the bottom of your tank, avoid disturbing the water. Instead, use a gravel vacuum to remove all the particles settling above, between, and below the substrates. Afterward, you can use a water clarifier to clean the water, making it crystal clear.

Gravel and sand residue is perhaps the easiest cause of cloudy water in aquarium to fix. A water change will help remove a portion of the dust that is floating around your tank…

However, the best solution is to just wait. If your aquarium water filter cartridge uses a fine mechanical media, such as filter floss, then it will eventually trap most of the dust that is floating. You could also use a good water clarifier to speed up the process.

Now, it’s likely that a small amount of the dust will settle on the floor of your tank. This dust will again kick back up into the water if it’s disturbed. Not to worry! This can easily be removed with a quick gravel vac – check out our gravel vacuum review to find the perfect one for your tank.

2. Bacterial bloom

Bacterial bloom is yet another issue deemed extremely common when the water in your tank turns exceptionally cloudy. When your aquarium is riddled with bacterial bloom or blossom, it often resembles a tank full of diluted milk.

This phenomenon occurs when your tank has excess nutrients, fish waste, or decaying food in the water and a limited quantity of beneficial bacteria to eat it. This situation tips off the system and forces the bacterial colony to reproduce more. The explosion of the population often makes the water have a milky haze.

If your water looks like a thick white fog, then you might be dealing with a bacterial bloom. Yep, that hazy cloud could actually be millions of tiny beneficial bacteria, swirling around your tank.

On its own, a single bacteria is invisible. However, as they grow in number, the group looks like a foggy discoloration in your aquarium.

Gross, huh?

What you are looking at is commonly called a bacterial colony.

Bacterial blossom is a common sight when cycling your aquarium. In some cases, it will be a mild haze, while in others, your aquarium can look like it’s filled with milk – it all depends on how many bacteria there are.


  • The leading cause can be introducing harmful chemicals or medications that are prone to kill or deplete the beneficial bacterial colony in your tank.
  • Sudden ammonia spikes from any organic waste produced by your fish can also result in bacterial bloom.
  • A new tank that hasn’t been appropriately cycled can also result in milky water.
  • A new big group of fish can cause this issue if your tank doesn’t have enough beneficial bacteria to support the tank’s ecosystem.
  • Replacing the old filter system with a new filter can also cause this issue.

How to get rid of it!

You do nothing. In a cycling tank, this bacterial bloom will disappear on its own. A week later, your cloudy water will be nothing more than a distant memory.

If you are not cycling your tank, then a bacteria bloom could be a big warning sign. You see, this bacteria commonly appears when decaying plants, rotting fish food or too much poop builds up in your tank.

If that’s the case, the first thing you want to do is grab your trusty aquarium test kit.

Got it? Good. Now, you need to check your ammonia and nitrite level to make sure they are both at zero parts per million (ppm).

If they have risen, perform an immediate water change so that no harm comes to your fish. Now, you have to figure out what the cause was.

This cloudy looking bacteria often appears when there is too much fish waste breaking down. The most common cause of this is overfeeding your fish. Not only will your fish poop more, but there will be uneaten fish food source rotting at the bottom of the tank syndrome – fix this by cutting back feedings and removing all the uneaten excess food and decaying excess waste from your tank.

Another cause could be that you accidentally killed off all the good bacteria in your cloudy fish tank. If you rinsed your aquarium filter media in tap water, the chlorine will kill the good bacteria, and you will have to cycle your aquarium all over again, with your fish still inside.

If you have changed your tank’s water recently, that can be a big reason for bacterial bloom. To get rid of this, wait for a week or two.

The cloudiness of your water tank should start to gradually clear up as soon as the tank’s bacteria reestablish again, thus forming a perfect aquatic system. Avoid changing your water constantly or using UV sterilization as it can further increase your issue of bacterial bloom.

However, if you feel that the bacteria bloom is caused by other factors like substrates, excess waste, or decaying food, perform a partial water change. One can also use a gravel vacuum to eliminate the tiny particles floating in your tank. Partial water change is the key here as it won’t damage the existing bacterial culture.

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07/19/2024 05:34 pm GMT

Green cloudy water in aquarium

Murky green cloudy water

Out of all the different colored clouds that will visit your tank, green cloudy aquarium water makes beginners panic the most. It just doesn’t look right, like pea soup.

If you inspect your water in a clear cup and see a shade of green, then the primary culprit is algae bloom. This issue is prevalent in tanks that receive sunshine daily.

In severe cases, your water will be so murky that you can barely see your fish.

So, what is this weird green fog that covers your aquarium?

Well, it turns out that it’s a particular type of algae bloom

Algae Bloom

Any aquarist with little experience with aquariums knows how common algae bloom is. Algae is a fully living microorganism that grows on the sides of your tanks and under/on the tank’s decoration.

These algae can profusely multiply if ignored, resulting in a tank full of green-shade water. One must note that algae always thrives on the exact requirements of any plant.

You will see a massive spike in algae growth if your tank has sufficient nitrogen and sunlight. Excessive feeding or fish waste can create extensive nitrogen, thus inviting algae to proliferate.

Since algae are living organisms, overpopulation of them can surely disturb your aquarium’s ecosystem and affect the fish and plants in your tank. Lastly, apart from changing the color of your tank, it will rapidly deplete the oxygen levels of your tank at night.

Phytoplankton is small. Really small. In fact, you can’t see it with your naked eye. But as it grows in number, it will become very noticeable, turning your tank water a cloudy green color.

But don’t worry! While it may not be pleasant to look at, this type of algae growth won’t harm your fish.


  • If your aquarium is directly exposed to strong sunlight, it will cause the algae to bloom uncontrollably.
  • Switching on artificial aquarium lights for an extended period can also cause this issue of algae bloom. 

How to get rid of it!

One must perform a water change as it is the most vital step to get rid of algae bloom. Afterward, address the overstocking or overfeeding to bring the spread in control.

The above remedy is to clean the water by changing the entire water volume of your tank. This step won’t reduce the algae growth permanently, so you need to move the location of your tank to a less sunny place.

If you use artificial lights, consider turning them off to prevent the algae from overpopulating. The last method uses a UV sterilizer to eliminate the algae-ridden water.

Ultraviolet radiation changes the algae’s cell structure, discouraging the algae from reproducing on a cellular level. After sterilizing, you can change your water and remove all the algae.

A UV sterilizer or fine filter media, like a polishing pad, will quickly put an end to this green cloudy mess for good – your water will be crystal clear in no time.

While this will fix the problem – the algae – it doesn’t stop the cause.

Unfortunately, there are a lot of different causes…

Most of the time, one of these is responsible for your murky water. Sort these out to prevent the green cloud from coming back!

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07/19/2024 06:10 pm GMT

Yellow or brown cloudy water

Yellow cloudy aquarium water

If your mug test shows a tint of brown or yellow cloudy water, then the sole reason is the introduction of untreated driftwood in your aquarium.

While it might start out as a yellow tinge, if you don’t stop it, your water will darken in color until it looks like a refreshing sweet tea.

The likely culprit?

Untreated Driftwood

Many aquarium hobbyists like to introduce natural driftwood in their aquarium to make the tank look appealing and exciting while giving their fishes something to rasp or nibble on.

We highly recommend adding driftwood to your tank as it is exceptionally helpful in dropping the pH of your water. This dropping of pH is an excellent way to naturally make hard water more gentle and suitable for most fish species.

So if you have recently introduced a new piece of driftwood in your aquarium, then it is the only reason for such yellowish-brown murky water.

Driftwood generally leeches tannins into the water, which gives it the brownish shade. The water first goes through a yellow tint and, with time, can turn into a deep brown color, resembling a shade of muddy water or exotic sweet tea.

This hue can also be caused by introducing leaves and seed pods into your tank. While these tannins aren’t necessarily dangerous for your fish, they can make the tank look muddy and obstruct the fish’s vision.

As the tannins slowly leach into your aquarium, it will turn your water a yellowy brown color.

FishLab Fact: Some aquarists want their aquarium to turn a brown color, adding untreated driftwood and leaves to darken the water. These tanks are known as blackwater aquariums, and while they may not appeal to everyone, they are beautiful when designed correctly.


  • The only cause of brownish-yellow water is keeping pieces of untreated driftwood, leaves, or seed pods in your tank.

How to get rid of it!

This tip is beneficial when you decide to change your driftwood. Consider pre-soaking and then boiling the wood before placing it in your aquarium tank.

Boiling speeds the process and gets rid of all the tannins beforehand. If you do not wish to boil your driftwood, consider soaking it into a storage container for a few days. Simply soaking can also get rid of the pigment.

If your tank is already yellow, remove the wood and give it a boil. This step will discourage the wood from leaching the tannings after putting it in the tank.

To clean the water, consider using a carbon filter, carbon pad, or Seachem Purigen. The activated carbon will soon get clogged with all the tannins, which you must dispose of. However, if you use Purigen, you can clean it with bleach and reuse it.

Exactly how many tannins are released entirely depends on the type of driftwood. Some woods, like manzanita, barely color your aquarium while others, like Malaysian driftwood, paint your aquarium a cloudy shade of brown.

Fortunately, most tannins can be removed by pre-soaking the wood before placing it in your aquarium. Boiling speeds up the process.

If it’s too late, and you already placed the wood in your aquarium, remove it and give it a good soak. Any tannins that you remove now won’t dye your aquarium water when you return the driftwood to your tank.

But what about the water inside your aquarium… The stuff that has already been dyed a brown or yellow color?

Well, using a carbon filter will remove any color from the tank, leaving you with crystal clear water.


As you see, cloudy aquarium water comes in many different colors.

We hope our write-up was helpful for you in understanding the real reasons behind the cloudy tank in your home.

We recommend that fishkeeping hobbyists keep these causes in mind and pay extra attention to avoid discoloration of water in the first place.

And while it might look ugly, you won’t have to put up with it forever. Whether it’s milky white or pea green, it’s easy enough to stop in its tracks.

Lastly, if you wish to prevent any bacterial bloom or cloudy episodes again, carry out the practice of seeding in your new tank. Seeding will indeed reduce the cycling time by half while reducing the likelihood of your water becoming cloudy!

How did you get rid of cloudy water in your aquarium? Let me know in the comments below!

Remember to check out these essentials for a clear, toxic free aquarium:

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 (73)

For the cloudy water (bacterial or algal) i used a UV filter 24 watt. Cleared in a day. Way cheaper than on going costs of chemical additives.

Hi Ewan,

I agree with you here. If you cannot deal with the cause a UV sterlizer works great – especially for green aquarium water.

I’ve a random question. My roomie and her boyfriend just got a 38 gallon tank. Managed to kill of three straight away by not depositing them properly (even I know how to do that and I’m not a fish person). This makes me think they haven’t done all their research.

I thought I was going crazy when I saw a few specks flying in the air in my room last night. I left the apartment and came home and their door was now open (tank is in the room). The hallway, her room, my room, BILLIONS. Of these things flying around. I feel like I’m ins miniature version of Frozen. Is this normal? She denies seeing them, but she’s also not exactly the most forthcoming or respectful. Or I’m just a bit observant as I sit in bed watching these things wondering if I’ll have grey hair in the morning. Is this unsanitary? Should I move immediatly? I’ve opened a window but I’m first level and don’t feel like having people watch my tv with me…

Any advice on what these are, how to get rid, CAN I get rid of she continues leaving her door open? I close mine but these little suckers are tiny.

Any advice appreciated as my fishie knowledge is limited.

Hi Liz,

That sounds terrible. I’m so sorry to hear about your difficult situation. Unfortunately, I’m not sure what it is you are seeing. It sounds like a bug infestation of some kind but I am not sure that it would have come from your roommates fishtank. I have never seen flying specs come off a fishtank, like you have suggested. Can you take a photo and post it on a bug identification forum?

We have a cloudy aquarium problem. Seems like no matter what, it won’t go away. Many mistakes. No solutions. Tank was fine Sept until about Dec. cloudy more or less, ever since Christmas.

I have a polishing pad in filter along w spimge, carbon, bio cubes? Have use bio products with water changes, water conditioners. No luck. Worried it might need to cycle? Unsure. It is a yellow/green cloudy? I think it might have been or also white cloudy. When I skim a cup it looks like light pee. Test strips show all looks in fine/neutral realm.

I am sure at some point I overfed, worrying about African Frog getting food. The fish often get to it first.

16 gal. 4 glow tetra, 1 moss ball, 4 penguin, 1 frog, 1 snail. Added to tank over time in that order. Got snail Thanksgiving weekend.

I have done 10-25?% or so water changes varying from every other day (10) to weekly (20 or so?) to couple weeks.

Perplexed n stressed. We don’t have another tank. The filter is a 30 running it high lately except for a couple minutes when feeding.

Clean gravel w water changes and have cut back feeding amount/frequency. Hope you can give helpful advice.

Hi Jenna,

do you have any wood in your tank perchance? Also, what are your water parameters like? Grab an aquarium test kit. 90% of the time this will clue you in as to what is going on in your tank. You should already have on on hand – it’s an essential aquarium tool. The API master test kit from amazon is the cheapest I have come across.

No wood. I have test strips. They all come out in the neutral/safe range? Had water tested in Dec. at the store before I bought the strips. Same readings since then essentially? I believe they are Tetra. One tests 5? The other tests Ammonia? Always come out fine?

I have a strong dislike for test strips, myself and many others have found that they often return a wrong result. That isn’t to say that’s what is happening here, but a test kit is more accurate and much cheaper in the long run (those test strips soon add up if you test at every water change).

Driftwood, dried leaves and other dry organics are usually the reason why water turns yellow.

Have you tried doing a 70-100% water change to see if it comes back? If your tank is fully cycled, this shouldn’t cause any harm. You could also do three or 4 back to back 50% water changes each day. If the water keeps staining then there is something in your tank responsible.

At this point, it’s a process of narrowing down what that could be. So start with the water. This will confirm that there is something in or being added your tank causing the problem. From here, you slowly swap stuff out and do the 100% water change again. Say, switch foods, see if it comes back. Remove carbon, see if it comes back. Etc.

Ok. Thank you. I am worried at some point I rinsed filter items in hot tap water? I have rinsed in only tank water since. I was using algae pellets. Stopped that. I did change carbon. I did add a polishing pad. I have used Microbe lift Special Blend larger 4-5 weekly doses and also Fluval bio should I keep using one of them? I also put in API stress once or twice. All dofferent recommendations from different staff. I used a color boost a few times for the Glow fish. It is a yellow/green color – so I wouldn’t be surprised if that helped w color? My last thought was to leave it alone and see. It is the only thing I haven’t done aside from 50-70 water change. There has been some improvement since last week? Couldn’t see middle of tank well. Now the front is more clear middle is so-so and back is foggy. But it seems to eventually get worse after I change water again? So worried about doing so now. So perplexed not sure anymore. And I was wondering about the UV filter. Also, worried if I did mess something up would the 50% or more water change cause a problem. I will invest in the test kit you recommend also. I am hoping once I check it today I will be able to see some any improvement or worsening so I can tell what’s what a bit? I have been making sure light on only 1-8 or so to keep that under control. I have even at times only kept the blue light on and put the room lights on. My lighting also affects the look. Blue light, vs. Day light, vs. the combo option. Sorry so long. Hope the extra info helps.
Thanks for listening!

Hi Jenna,

It sounds like it has been a long journey. Hopefully we can figure this out. It certainly is possibly that something you have added has been responsible. The first step is to confirm your water parameters with a test kit, as it is possible when you rinsed the filter in hot tap water you killed the beneficial bacteria.

As long as you are using a water conditioner, and your tank isn’t cycling, a 70-100% water change won’t affect your tank at all.

If your tank comes back with good parameters, I’d stop adding color boost and any other chemical additives, including microbe lift. Then I’d wait after the water change to see if the color returns.

Just the standard daylight throughout the day then off at night will be fine, to simulate a regular day/night cycle.

If you look at your polishing pad, has it trapped any yellow/green colored gunk? If not, then the water is stained rather than colored by anything floating around in it. In this case, A UV filter won’t do anything since the water is stained.

It will take some time to find the cause, and a little trial and error. But step 1 is the test kit. Step 2 is the water change. Step 3 is halting the chemical additives and go from there…

Hi Ana,

Yes, but you need dechlorinator (water conditioner) first. Otherwise you’ll kill anything inside.

Hi Ian,

Back again with an update. So I was so anxious, before I saw your last reply, I went ahead and did another water change. It appeared to me maybe the tank was starting to look worse again and as it was now 1 week + 5 days since the last change I figured waiting 2 more might only make it worse (as I don’t think it was the same or better on day 5).

For clarity (no pun intended 😉 I am replying also to some of your comments here… used lines to help delineate. 🙂
“It certainly is possibly that something you have added has been responsible. The first step is to confirm your water parameters with a test kit, as it is possible when you rinsed the filter in hot tap water you killed the beneficial bacteria.”
Jenna: OK
“As long as you are using a water conditioner, and your tank isn’t cycling, a 70-100% water change won’t affect your tank at all.”
Jenna: I did use a water cond. unsure if tank recycling? How would I know? 🙁 When I panicked before your last reply I did maybe a 4 gallon WC? Got a lot of junk out as usual. (I think in my early cleans I was less skilled with the vacuum which I’m sure added to the issue.) Following last WC water still Cloudy but Better. Could finally make out the strands of the purple plant in the back of the tank.
If your tank comes back with good parameters, I’d stop adding color boost and any other chemical additives, including microbe lift. Then I’d wait after the water change to see if the color returns.
Jenna: To be clear it has been hazy and colored. Ha again no pun intended.

TEST RESULTS: My daughter and I had fun playing Scientist! 😉
ph: 7.6 HRph 8.0 Ammonia – .25 Nitrite 0 Nitrate 0

Worried. I tested Ammonia again this morning. It is hard to say, maybe at closer to 0 or less than .25? Last night seemed a lithe more yellow/green. This morning seems more yellow but maybe slightly still yellow/green?
Just the standard daylight throughout the day then off at night will be fine, to simulate a regular day/night cycle.
Jenna: OK I HAD THE LIGHTS MORE OFF AS I READ SOMETHING ABOUT LETTING GOOD BACTERIA GROW AND ALSO THAT I MIGHT CAUSE MORE ALGAE GROWTH? EVEN FREE-FLOATING ALGAE? But I was trying to keep them on some for the frog especially? I read they need day/night time.
If you look at your polishing pad, has it trapped any yellow/green colored gunk? If not, then the water is stained rather than colored by anything floating around in it. In this case, A UV filter won’t do anything since the water is stained.
Jenna: It has some algae but I wouldn’t say it’s colored the filter? It’s looks mostly white with dirt some algae pieces here n there. It’s been in about a week or so.
It will take some time to find the cause, and a little trial and error. But step 1 is the test kit. Step 2 is the water change. Step 3 is halting the chemical additives and go from there…
Jenna: Thanks. ***As of now. Frog and fish look fine still? Water looks cloudy still.*** But still better (seeing plant in back) than before WC. Doesn’t appear better than yesterday. Maybe worse. Hard to tell. I also think I still added a Bio-something. Whatever was recommended when I do water changes/ to start the cycle in my tank. But No color boost for the Glow Fish. And as stated Ammonia could be .25 or maybe closer 0 now. Maybe it is morning light too?

Thanks for your input. You have been more helpful than all the stores! If you could advise on further action/inaction it would be much appreciated.

Hi Jenna,

Going off your test results, the tank is in the very early stages of cycling. Once its done you should expect to see 0 ammonia, 0 nitrite and some nitrate. Both ammonia and nitrite will rise before decreasing (not at the same time) before you see this though.

That haze could just be the start of your tank cycling. In the early days, bacteria bloom often appears. It will go away on it’s own if this is the case.

Here is a shot of the different colors for the API ammonia test, to give you a better idea:

Please note, the exact colors here will depend on your computer screen, but if you have brightness turned up it will be near enough.

Unfortunately, much of what happens in aquariums is a waiting game. You’ll need to be patient here. That’s most of what cycling is, using your test kit results to guide you.

Ugh. So frustrated and perplexed??? We were out and upon return I checked the tank. It looks More cloudy than this morning. 🙁 Thought maybe we would finally turn the corner here. Just rechecked Ammonia. I would say it looks like .25 mm again. If it makes any difference, I still have this mornings Ammonia sample and it definitely looks like 0ppm now? As this morning I was unsure if it was 0 or .25? Not sure if that is just from it sitting all day. But definitely this new sample looks more like .25 mm a yellow green color. 🙁 I am at such a loss. Do I change the water again? Do I leave it go? More testing? We seem caught in a constant loop of cloudy to better to worse changing water or not. I can’t find any other info online for Constant Cloudy Water. I ALSO just tested Nitrite – still at 0 and Nitrate – looks like 5.0 today? And unsure if last night there was an error in the Nitrate number as when I tested it this second time, not sure he narrated the correct instructions to me. Yet one more inconsistency. Hoping you can spare some insight.

Hi Jenna,

Hang in there, this is to be expected. As per your previous results, your tank isn’t cycled. Also, please refer to my previous comment reply on ammonia color.

This guide will get you up to speed on cycling your tank:

As for the nitrates, I would test your tap water add some to a glass, add your water conditioner then test. It’s not uncommon for tap water to have 5 ppm of nitrates in certain areas of the country. If it reads zero, double check your testing in your tank,

Hi Ian,

You said exactly what I had hoped you would Not re: cycling. 🙁 But I am still a little confused. I have read about the cycling. Regarding the water change cycling. Isn’t that what I have essentially been doing? How is it in All this time my Ammonia has not risen to danger and/or my Nitrites? I have been so worried I was testing often. As they did not show on the test strips? (Picked up in Dec.) Wouldn’t there have been some sign? And if not – was it due to my WC’s? Why hasn’t my Nitrate risen then? And why still the slight ammonia I see now? Extra note: I saw about Not turning off your filter. At one point mine stopped working. I had another I used until the other came back to life. This happened once or twice over the time since Dec.? Not sure if that was yet another wrinkle. Tank filter did come back to life after some settle time 12 hours or so, maybe more. The human error is endless here.

Test results today: The Tap Water – I accidentally tested without Water Cond. first. Nitrate was at 5ppm. With the water conditioner it was at 0 ppm.

This mornings tank readings looked like: Ammonia – 25 or less? Still hard to tell. Thanks for photo. It is Not 0 I believe. But it could be less than 25? It seems to have some slight green not full yellow to me. Nitrite – still 0 Nitrate – I think it is still 5.0 ppm? It could even be a bit more, but Not at 10 ppm. Out of curiosity I tested High ph again – had an extra water sample looked more like 7.4 vs. 8.0 Fri night?

I am guessing it is the lack of Nitrate that leads to the idea of it not fully cycled? And the fact that I am not at 0 ppm Ammonia?

I just don’t get how this has not shifted given it has been since December? How has the Ammonia/Nitrite not increased in all this time? I have been adding a Bacteria boost also with every water change. Probably the whole time I have had my tank? Either what they gave me Fluval to start my tank or the Microbe Lift Special Blend – when the cloudiness wouldn’t go away? Has that helped with the Ammonia/Nitrites, but just not enough?

Just a little more info. Curious I tested with my Test strips today Ammonia – Ideal 0?
Nitrate – 20 Safe, Nitrite 0 Safe, GH soft/hard KH between 0-40 low? Ph around 7.2
So I would have thought fine. As I have all along.

And I happened to have old test results following latest water change Thursday? Would make these results from store Test Strips/sales clerk.

Ammonia – Ideal 0, Nitrate – 20 Safe, Nitrite 0 Safe, GH 75 soft, KH between 40, Ph around 6.8 – So again all seemed fine based on what they said?

Likewise I happened to Still have my results from first Water Test at the store which was actually back on 12/8 so it was cloudy then.

Ammonia – Ideal 0, Nitrate – between 0-20 Safe, *Nitrite 0 Safe – 2 records? one is between 0-5, the other has 1.0 circled?*, GH 150 – I have since then added salt at times (was told it would help), *KH between between 120-180*, Ph around 6.8

Note: Not sure what led to the difference in my KH over time? also, the Nitrite discrepancy, I think I questioned her judgement. Can’t remember, but I think I led her to the 1.0 over the .5 but maybe not. Not sure if this early info gives any additional insight?

Also, would Really like to know if you think I should do a water change Tonight? ASAP? As it Looks worse than just the other day (when after larger WC it looked somewhat better, I am VERY tempted. 🙁 It does not look as bad as other times when I couldn’t make out the faces on Bear Cupcake Castle. I am just trying to not kill off 1 or more of my daughters only pets.

Thanks in advance for your insight. If I am will be doing the fish-in cycle (as I have no other option) I will need to get some supplies. I am at a loss right now for Where I would be on the Cycle? Step 3/4? I will post future comments there, if that is indeed where I am off to…

One more note… My original test results from Friday night were entered incorrectly with my posted comment. I have a new data sheet and reviewed post and saw the discrepancy.

Here is what I posted:
TEST RESULTS: My daughter and I had fun playing Scientist! ????
ph: 7.6 HRph 8.0 Ammonia – .25 Nitrite 0 Nitrate 0

But what I have written down reads 5.0 Nitrate – still can’t remember if the shaking happened all though the test. It gets a little chaotic here at times.

So again not sure if this extra corrected info, gives any new insight on my the last comment I also sent moments ago. Sorry. So many inconsistencies etc. Mercy please. ADHD here.
The last time I kept an aquarium the there was no internet. I just based what I did on books and past experiences with older sister’s aquarium. Leaning a lot on this new tank! 😉 Bear with me Aquarium! 🙁

So the 5 nitrate is likely coming from your tap water once the water conditioner wears off. No biggy. This is well within the tolerable rage of fish. You just need to be mindful that 5 is the baseline, not zero, when testing.

It’s possible something you are doing, adding or have done to your aquarium is killing off the beneficial bacteria. There are thousands of things that can do this, so I cannot narrow it down for you, a few could be removing the filter media, chemical additives, stopping filter flow, etc. Remember, it might not even be a single thing but multiple. Only you will be able to narrow this down. But as long as the bacteria keeps dying/doesn’t grow, your tank will be perpetually uncycled.

If I was in your position, I would perform a 100% water change and stop adding anything to the tank besides water conditioner. From here, attempt to carry out the cycle. If it’s a bacterial bloom from cycling, the cloudiness should come and go.

You would be at step 4 in the fishless cycle. Just keep monitoring that ammonia and keep it at around 0.25. From here, you should see nitrites within 3 weeks and from there it’s just more waiting.

A lot of fish keeping is patience, testing and waiting. I know all this info feels daunting, but trust me, it definitely gets easier. Hang in there.

Ok. :l So as it appears we are not dealing with a bacteria bloom or at least need to move on to cycling, I will take my questions up over there. Thanks Ian!

Hi Ian,
I have read your responses and greatly appreciate your time spent answering all these questions. Especially those from Jenna. Cudos to you. Hard to find anyone willing to express this interest in helping others. I am an avid aquarist with many, many tanks in the house. I have one with my Flowerhorn (Elvis). His tank is cloudy. It’s not murky, just a little cloudy. Enough to irritate me as it sits beside all my other tanks which are all Crystal clear. While it was in this state I removed his tank mate a 12″ pleco. I assumed it was the additional fecal matter was the possible cause but. All levels are all below acceptable levels.
I use two aquaclear 110 on his 75 gal tank. He is about 8″ and I really want to see him clearly. Getting pissed off.
I am looking for something I may have missed.
I do 10 to 25 percent WC weekly on all my tanks. All water is conditioned all feeding is regulated. He is the only fish, been slightly murky for about 2 months and won’t go away.
Any thoughts

Hi Bill,

Always nice to meet another passionate fishkeeper!

Thanks for the kind words 🙂 I don’t have all the answers but I do try help to the best of my ability.

Elvis is an awesome name for a Flowerhorn! Was that intentional because of Elvis Presley’s hair?

It’s honestly hard to say with the info provided here, what else is in his tank? Also, does this tank have a lid? Also, what color is the cloudiness? Could it possibly be an algae bloom that has taken hold from before when the pleco was in the tank?

It still could be because of the pleco. have you used a gravel vacuum since removing it? It’s possible all this fine sediment hasn’t been removed.

Also, have you tried running filterfloss (say, 50 micron) on the tank? It’s possible that whatever is clouding up your water is a fine sediment that is so small, it’s passing through your filter. Filter foss works wonders for trapping minuscule sediment. If you aren’t, and would like to consider it, place it behind your coarser media, so it doesn’t become clogged as quicky.

I’m just spitballing here. Given your expertise, you have probably already considered these options.

Can someone tell me why my test results for nitrate comes up clear,(meaning the water color is clear). API chart shows should be yellow for a 0 reading. I get the same results in 2 different tanks. All other readings are good except the PH in the fish tank is pretty high, but the other tank with red rili shrimp is with in peramaters for shrimp. I have used PH down in the fish tank. Both tanks are reading 0 ammonia and 0 for nitrite.

Hi Wrendy,

Do you have a bottle #1 and Bottle #2 for nitrate? Have you followed the instructions step by step? If you deviate from these, it can cause issues.

Hi Ian,

Thank you so much for this forum and for answering people’s questions. I have a question :). The water in my 20 hex tank has turned slightly milky white. It is a new tank. Brand-new. I set it up 10 days ago. I was very car full to wash the gravel. I believe gravel is thoroughly washed. It has plastic plants in it. No real plants. I let the filter and heater run for a few days with no fish. Then I put some of that Starter Bacteria kit stuff in there? Made by API. There’s like 3 packets I put into there on day1. Bacteria, salt, and something else I forgot sorry. Then on day 14 same. Then on day 28 same.

On day 3 I put 7 medium tiger barbs in there. Water was crystal clear. Just after I started feeding them high quality fish flakes, water started turning white. I assumed it was excess food. Tried less food. Still there. Put extra filter pad in filter and put clarifier in there. That cleared water until next feeding. More milkiness.

I’ve been using test strips and the results indicate perfect water

Is it the flake food? Does all flake food do that? I’ve never had fish before so I don’t know anything lol. Should I start using fresh live or frozen food? Should I wait for bacterial bloom/cycling thing to clear it all up? Thanks in advance!

Hi Jim,

Thanks for the lovely feedback. Now let’s see if we can’t get to the bottom of your cloudy mystery.

I personally don’t trust test strips. Myself and many other fishkeepers have either had false positives, or a falsely returned reading of zero. I recommend grabbing an aquarium test kit (I use the API Master Kit, it’s the cheapest.) It’s considerably more accurate, having a test for each parameter and will last for more tests than strips, which saves money in the long run.

Now, it is possible that your test strips are right, but having helped others out where the strips returned a wrong reading, I cannot be 100% sure. It is possible your tank has not cycled yet. 10 days is right on the short end for a cycle. 3 days was almost certainly uncycled and too early to be adding fish, so it’s entirely possible that your food + poop/urine from the fish contributed to a bacteria bloom, which clouded up your tank.

It’s possible that the clearing of the milkiness by use of clarifier + filter pad was coincidental with the bacteria running out of “food” and dying off.

Flake food shouldn’t turn your tank a noticeably milky color, this is not expected.

First, When you say “test strips results indicate perfect water,” What does the each of the ammonia, nitrite and nitrate indicate, in ppm?

This will give a clue as to how to progress.

Yes maybe it is a bacterial bloom. Indeed adding fish on day 3 from setup was early, The instructions on the API “Perfect Start” regimen said I could add 3 tropical fish per 10 gallons on day 1. Mine is 20 gallons so I added the 7 tiger barbs. They are all still alive and seemingly healthy today. But yes, hopefully it’s just a bacterial bloom.

Ok I will get the better test kit that you mentioned. All I have for now are these Tetra “EasyStrips”. As you know, each parameter has bands of color. Based on those bands, here are the results which have been consistent with all past test strips:

Nitrate, between 0 and 20 ppm
Nitrite, between 0 and 0.5 ppm
Total hardness, 150 ppm
Total chlorine, between 0 and 0.5 ppm
Total alkalinity, 80 ppm
pH, between 6.8 and 7.2

If those values are accurate, are they reflective of a bacterial bloom? The water is still cloudy despite a recent 25% water change and use of three new filters. Thanks so much for your help,

Hi Jim,

These companies promising “instant cycles” on day one are the worst for the aquarium hobby. They prey on beginners who don’t know any better. From a new setup, for a beginner, there is no way to cycle a tank in one day without access to an established tank. A big problem is that to a beginner, fish don’t have expressions or give obvious clues that they are stressed, until it’s too late. Because of this, fish can look perfectly healthy, even when they are in stressful conditions. None of this is your fault, it’s the company’s that take advantage of you.

Unfortunately, it appears your test strips are missing one of the most important tests of all: Ammonia. As a result, it is difficult to say what stage of the cycle your tank is in and how to best react.

Once you have your new test kit, I would suggest following my fish-in cycle guide.

Hi Ian,

Thank you so much for your help. I bought the master test kit as you said. Ammonia is at 2.0 ppm with 0 nitrites and 0 nitrates. Yikes. Ok I will do the emergency fish-in cycling as you suggested but I have a question about the instructions you wrote:

Step 4: Dealing with Ammonia, you said “Keep dosing and using your aquarium test kit daily. At this stage, you need to perform a 50% water change.”

At what stage? Before I start putting the Seachem Prime in? Or after 7 days of putting in the 2 doses of Seachem Prime everyday (i.e. after 14 doses)? I guess the real question is, when doing emergency fish-in cycling, using the Prime method, exactly when should 50% water changes be done? Can I be changing the water too often to point where fish are harmed even more than already?

Hi Jim,

Yep, your tank definitely needs to be cycled. I would treat the first day you start testing as day zero of the cycle and go from there.

I need to clarify this part when get a chance, it’s similar to the next step for nitrites. Prime can only deal with up to 5 ppm of ammonia. As it gets to 4 ppm, you should do a water change, to keep it within treatable limits. a 50% water change will roughly cut ammonia and nitrite in half.

Water changes are considered harmless to the fish. In fact, if you don’t use seachem prime, you will be balancing the ammonia and nitrite with near-daily or even twice a day water changes.

In a fish-in cycle, there is no set schedule for a water change. You perform a water change as your test kit dictates.

Please let me know if I need to clarify this further.

I’ve been keeping fish for years but I’ve never had this particular challenge. To make a long story short, my 7-year-old is the proud new owner of a betta which she has been responsible for feeding. Everything was fine until a few days ago when she accidentally spilled a full container of food into the tank and was afraid to tell me. I’m not sure how long it festered but when a garbage smell came wafting out of her room it caught my attention and the tank was all brown and scummy and opaque. I thought for sure the poor little guy would be dead, but he was ok and I transferred him outta there. I emptied 98% of the nasty sludge water and did my best to clean the substrate, then I dropped in some peppermint oil (natural antifungal) and left it for 24hrs.

The problem is it’s a “dirted” tank with plants. I took all the peppermint water out and removed and rinsed some of the substrate. The filter got a thorough rinse. The smell seemed to be gone. I filled the tank half with water from a healthy aquarium and half with dechlorinated tap. The fish was acting super agitated in the jar he was in (poor little guy) so after an hour or so I put him back in the tank. This was at night. By morning the tank was cloudy white, the smell was back and it’s getting stronger 🙁

I really want to avoid removing the substrate if possible, because I just installed it a few weeks ago. Do I have any other options?
I’d really appreciate any suggestions. -Jen


The problem with that “aquasoil” is that it’s porous, so it’s possible you will still need to change it if it’s causing the stench. What’s far more likely is that you crashed your cycle. Adding water from a good aquarium won’t bring it back. The peppermint oil and filter clean would have killed any beneficial bacteria (good bacteria that keep water safe) the cloudy white color you see often accompanies the cycling process and will go away on it’s own. Generally within 2 weeks.

For more info, check out my fish-in cycle guide

Hi, Ian,

I am trying to clear up a bad algae bloom in a 9 gallon Fluval tank. I bought the 3 watt Green Killing Machine UV sterilyzer and put it in the tank yesterday, but don’t see any difference. Do I just need to be patient? Should I do a water change in the tank? I have a 2.5 gallon Fluval tank that has no issues and has been cared for/cleaned the same way as the larger tank — we’ve had the bigger tank for about five months and cycled it properly before adding the fish. Thanks for your guidance!

Hi Mary,

If it’s a live, free-floating bloom, you’ll likely just need to be more patient. While the UV light does “kill” these tiny organisms, they can still float around for quite some time, this can be further complicated by just how much water movement is in your tank – they may not settle at all. Depending on just how bad the bloom is, a water change can certainly speed up just how quickly you see results!

Not a problem Mary, I hope that this solves your hazy water, so you can go back to enjoying your fish 🙂

HI, I have just bought two coldwater rosy barbs , 2 days ago and now the water has turned cloudy you can partially see through it from a distance. I do not know what to do and I think it is because my brother added too much food?

Hi Priya,

If it’s from food, perform a couple of water changes and monitor your nitrite, nitrate and ammonia levels. If it doesn’t go away then it’s an organic growth rather than too much food.

Hello, we have well water with a softener, my 50 gallon fish tank water is cloudy even after a water change, new filters the whole nine yards. I can’t seem to get it clear. I have tried clarifying it, but it still will not clear up. I use a suction hose so I know the gravel is clean. I only have about 12 fish plus 5 small cory’s and one sucker mouth. Can you give me some advise on what can help? I had fish tank when living in the city and have never had cloudy water

Hi Elaine,

Is this a new setup? Swapping out filters is going to crash your tank and force it to recycle, which is often followed by cloudiness. If you test your ammonia, nitrite and nitrate levels, what do they read as this can give you clues as to what is amiss in your tank?

Hi we have a water softener and a 55 gal tank with two filters on it. Maybe about 12 fish on it my tank is cloudy I check my nitrate levels they are 20 and under my ph levels are 6.5 it is a fresh water tank. We took out 50% of the water changed the filters added a water conditioner from top fin that pet smart recommended and our water is still cloudy is it because of the water softener water we have coming into our house. I also put a stress coat from api in the water so my fish won’t be stress or during the water change. I don’t know what else to do we have even went so far as emptying the tank all the way out and cleaning the gravel and decorations and filling it back up and it would look good for about a week then it would get cloudy again please help we don’t know what to else to do. Please and Thank you Melisa

Hi Melisa,

There really isn’t enough information to go off here. When you say you change the filters, are you referring to those disposable ones? They are somewhat of a scam as your beneficial bacteria lives in your filter and each time you throw away your filter inserts, you are getting rid of this good bacteria. This might be the cause of your constant cloudiness.

Came to this because I have a new aquarium set up 2 weeks ago, and I waited a week to put the fish in. Today my aquarium is cloudy. so are you saying we shouldn’t change the filter inserts? Should we instead rince them with some water from the aquarium?


Welcome to the hobby! I know it’s a lot to take in but hang in there, you’ll be a pro in no time.

Did you cycle your tank? Or did you just “wait” – If you just waited, I recommend checking out my fishless cycle guide

If your filter has those “disposable cartridges” I recommend swapping over to a filter that has room for ceramic rings, it’s here most of your beneficial bacteria will live – this way you can discard the sponge and it won’t crash your cycle.

You are correct that rinsing is preferable but the ideal is not relying on disposable filter cartridges at all!

When you say you cleaned the whole tank by emptying and cleaning gravel and filter etc was this all done at the same time. If so you will have killed all your beneficial bacteria and I turn will cause your aquarium to spike in ammonia,nitrates etc. If you do partial water change then leave filters etc and clean them after few days. Do maintenance gradually to avoid shocking your aquarium.

Hi Ian,
I have a 75 gallon tank with 2 Marineland Penguin 350 HOB filters. In each filter I have 4 of the Marineland refillabe media cartridges. Two of the cartridges have matrix and the other two have carbon. I have filter floss first towards the back of the filter then the cartridges with carbon then a micro poly floss then the cartridges with the matrix then the bio-wheels. This is the setup of both HOB filters. I washed my gravel, decorations well. Most came out of my old 20 gallon tank. At the time that I set up this tank back on the first Saturday in Jan, I only had two goldfish. One is a large fantail and the other one was a red cap oranda. The Red cap has since died. I waited 3 weeks before I did the first water change. I only did it because the water was turning brown. I did a 20 gallon change. I waited another 2 weeks before I did another change. I add prime to my water before I put it in the tank and add stability as well. My tank has never been crystal clear. I went through a month of changing the water every week from 20 gallons to as much as 50 gallons with the advise from a local fish store. I check my water once a week.My numbers are always roughly the same. GH 143.2 ppm, KH 53.7 ppm, PH 7.3, Ammonia 0.25 ppm, Nitrites 0, Nitrates 40-80 ppm. The only ones that varies is the Nitrates and GH & KH. You would think after 6 months, the tank would be clear. I am lost.

I now have a black moore, a blue oranda and another fantail to go along with the original fantail that is as big as my hand.

Hi Scott,

I’m terribly sorry to hear about your troubles. In a cycled tank, you shouldn’t be reading measurable levels of ammonia. Are you able to narrow down the cause? Also, 40-80 ppm of nitrates seems a tad high. Ideally you want to get it below 10 with it reaching a max of 40 before the weekly water change. Also, what’s your tank maintenance routine like? Are you doing weekly cleaning and gravel vacuuming?

I have only been doing 1/3 water change about 3-4 weeks. I always vacuum the gravel. I did a 40 gallon change 2 weeks ago. Even after the 40 gallon change, the water still was not perfectly clear. I checked my filter media and every thing was still clear. There was a little debris around the outer edge of the filter pads. I did another water change this past weekend, 30 gallons. This helped somewhat, but there is still a white cloud. Not as bad as the previous week. I would if it is the matrix that I have in my filters or my artificial coral insert. I have had it for a year now. It started in my 20 gallon tank. I thought by upgrading to a 75 gallon tank from a 20 gallon tank and having 2 hob filters rated for a 75 gallon tank each, would make it easier. I shouldn’t be doing water changes every week with this tank. The 20 gallon tank was fine by only doing a water change once a month. I just don’t get it. Very frustrating.

Hi Scott,

It sounds like you need to check your water parameters first, to ensure nothing is amiss here. What does your aquarium test kit say?

Hi Ian,

When I test my water weekly, the result are often the same as except for the Nitrate that varies. My GH is always 6-7, KH is 3-4, PH 7.3 -7.5 average, Ammonia 0- 0.25, Nitrite 0 & Nitrate 20-80 depending how long after a water change I test. My water straight from the tap test GH 7, KH 3-4, PH 7.3-7.5, Ammonia 0, Nitrite 0 & Nitrate 0. I am thinking about doing another 30 gallon change this weekend and take out the Matrix and fill with the media cartridge with carbon only. This would be 4 media cartridges per HOB filters with carbon or should I leave the matrix and take out the coral insert? Another question for you, Should I add Seachem Stability every single time I do a water change. After talking with a local fish store, they recommended only adding stability with new fish or once every couple months. I have not added any with these two last water changes. I use the API Freshwater Master Test Kit and the API Test Kit for GH & KH. I cover my tank at night before bed with towels to keep the undercounter kitchen lights from shinning in the tank at night. I under cover the tank and turn the lights when I get up to leave for work to check on the fish and feed them once a day, every other day. I then turn the light off before I leave for work. Then I turn the lights back on when I get home around 5:30-6:00 and leave them on until about 10-11:00 at night.
Is there a way that I can upload a picture of my tank?

Hi Scott,

I wouldn’t advise replacing the Matrix as this is where you beneficial bacteria hides. If it’s in your filter and you swap it out, you can crash your cycle. When swapping out biomedia, it’s best to do it half at a time, this way the beneficial bacteria hiding in your old media will migrate to the new.

I agree with your local fish store – it sounds like you have a keeper since they didn’t take the opportunity to sell you a product you didn’t need. If your tank already has beneficial bacteria colonizing the biomedia, there isn’t a reason to add more.

Unfortunately, I know more about fish than computers and don’t have a way to share photos to the site.

Your test kit levels sound like they are fine, although it should be 0 for ammonia. If it creeps up, it could be the cause of your cloudiness. If you are reading your test kit in natural daylight, you should be able to tell the two apart.

Are you sure the cloudiness isn’t caused by a failure to trap the really tiny particles floating around your tank? Filterfloss (50 um) is considerably finer than most aquarium sponge, especially those on disposable cartridges – it also can be squashed into place so water has to flow through it rather than around it, resulting in more effective trapping of sediment and gunk. You can pick a slab up for fairly cheap and cut it to size, a slab can last years.

I just check my water. This is after a 30 gallon change 2 days ago. PH 7.5, Ammonia 0.25, Nitrite 0 and Nitrate 40. I did not check the GH or KH this time. I also did not add Stability either.

I am a new fish owner. Just bought a 5 gallon tank for my granddaughter. Upon set up the water was crystal clear, now, today it’s a little foggy., not bad, but kinda fuzzy looking. I have a snail, two black mollies, a beta and 3 tetras. They are all doing fine, no problems, just the fuzzy looking water. What should I do to get it clear again??

Hi Sandy,

It sounds like you didn’t cycle your tank, unfortunately, this is skipped by a lot of people new to the hobby as big box stores like Petsmart and Petco often don’t highlight the importance of this step.

Read my fish-in cycle guide on more info on how to proceed.

Well I’m still at a loss. My tank has been white hazy for almost two weeks. Nothing major, but definitely not as clear as it used to be. The tank is cycled and all of the levels are within acceptable parameters and have been for at least the last 6 weeks. I have a 20 gallon long aquarium with 1 betta, 6 small platies, 3 small cory catfish, 1 mystery snail and 2 kuhli loaches. I feed them once every other day and only what they can eat in about 5 minutes. I use well water from the tap that has sat for 4-5 days before using it in water exchange. Once a week I do a partial water change to keep the nitrates under control.

Hi Melody,

When you say “acceptable parameters” What are the exact measurements of:


Dear Ian & Others

I’ve The Same Problem. My Tank Size : 120CMX45CMX45CM Approximately 245L. With My 9 Lovely Goldfish (1 Jumbo Size 20CM And The Other 8 In Between 8CM 12CM)
I’m Using Submersible UV LAMP, Submersible Pumps, Heaters And Aerators.
Sometimes I Use Drinking Water With 8+ pH
Sometimes I Use Tap Water Then Added Tetra AquaSafe.
KH In Between 35.5 – 4

I Changed The Water 25% – 50% Once Or Twice A Week.
The Water Looks Fine But Only For Couple Days. And After That Became Cloudy. White Cloudy Water.
Once Become Like Milk. Once Become Green Cloudy.
I Added Tetra Crystal Water. Still No Effect Until 48HOURS. No Crystal Still Cloudy. Even Worst pH Become Low : 5 And Some Of My Kidz Getting No Well.

I Use 2 External Top Filter (@ 60CMX17CMX22CM)

The Filter Media From Tank Are:

1. Jap Mat
2. Bio Foam 2CM
3. White Dacron
As Mechanical Filter
4. Zeolites
5. Super Bio & Crystal Bio (Pumice)
6. Bio Rings
7. Bio Balls
As Biological Filter
8. Carbon Active
As Chemical Filter

9. Water Flow To Tank

Do You Have Any Feedback
Thank You

Hi David,

What are your:



Also, the fact that your pH swings from 8 to 5 is problematic is this common or was it only after adding Tetra Crystal Water?

Also, do you dose with fertilizers?

Thanks Ian this article was very helpful. I bought a product years ago that is a small nylon mesh pouch filled with about a cup of tiny white plastic beads with microscopic sized pores. I think it was called a water softener/polisher, I can’t remember if it was either or both. I have been looking to buy another for my new aquarium but I can’t find the product in my searches online. Mostly because I can’t remember what it was called. It needs to be soaked in bleach every few months to recharge and while it’s fresh it cleans the water to a completely invisible level of clearness. I was hoping you might know the name of this product.

Hi Darren,

It wouldn’t be Seachem Purigen, would it? It needs to be recharged every few months and works similar to what you say. I don’t think they come in a nylon pouch anymore – you need to put it in your own filter media bag. Be careful which one you buy, purigen is darn fine stuff and can slip through the gaps in coarser media bags.

I used to always get white and green cloudy water
The green is very light though. Once I saw it I decided to by API ACCUCLEAR and it worked after 12 hours it was crystal clear than after a few days it was not that clear but was still good.
After every filter cartridge change or just washing it the water gets white than I realized that the dirty water in the bow flew through into the tank. HORRIBLE then I was more cautious so it stopped. Also, when I got my gravel I actually DID FORGET to rinse it and caused an issue of murky water (Yellowish-white) but the filter took care of it. I was lucky as I only got fish 10 days later. but every time the water gets cloudy all my other fish are ok but my 27 guppies just crowd near the top left corner. I don’t know why

Thanks for the article. I am stumped. I did a homemade CO2 (Sugar, water, yeast, baking powder mix) to try and get my plants going. Came home a few hours after setting it up and tank was milky white! So far I have
1. Tested water – Amonia – 0.25 ppm, PH – 6.4, (normally around 7.2ish), Nitrate NO3 5.0ppm, Nitrate NO2 – 0ppm
2. Have done two 40% water changes which seems to improve things a little but not clearing up completely
3. Theres a fine mucky looking growth on a lot of plants now, and a film of it on top of substrate
4. Just turned off lights to see if that might diminish this algae bloom(?)

Any thoughts would be appreciated

Hi UncleMo,

Unfortunately, I do no have a lot of experience with home-made co2. Is it possible the sugar or yeast contaminated the tank somehow? Also, that readable level of ammonia is troubling. Is it possible your tank is re-cycling and you are seeing a bacterial bloom?

None of these are the causes in my tank. I have a 75 gallon with a blood red parrot, a Jack Dempsey, I had two Bala sharks but one died right away so was returned and refunded the money paid, two convicts, and one pictus cat. I had to move the female convict because she became prego and became very aggressive. I’ve tried to put others with her but she immediately tries to kill anything I put with her.
She’s in a 29g by herself and the fry (I recently rehomed the fry) but all the sudden my tank is super cloudy. I perform weekly water changes as well as testing. All tests are normal and I did a water change in the middle of the week and still no change. I do not have any live plants or driftwood in the tank. The tank was cycled in August 2019. It’s now January 2020 so it’s not a cycling issue. I did recently stop a brown algae issue but that was a couple weeks ago. So any ideas what the cause may be? It seems none of the possible reasons in this article are the issue. I’ve changed filter. I rinsed the bio media sponge when I did a water change, I used the water I removed to clean the bio media. The convict seems to be doing fine other than she is looking for her mate so I’m not worried but I am in case this is the beginning of a serious issue. I have test strips and drops. All tests results are the same and all good.
Any ideas?

Ammonia- 0ppm
KH- 120-180ppm
PH- 7.5

Hi James,

Unless you just did a massive water change or have nitrate removing chemical media or otherwise, zero nitrate isn’t a good test result. In a healthy tank, nitrate is forever rising and a result of zero isn’t common. It could be a clue that something isn’t right in your tank. Are you reading your test kit in natural day light? Indoor lighting can make it difficult to color match and can really throw off the results. If your results are correct, this should be the starting point of your investigation.

Hello Ian,
We just took up the hobby and love it, my wife even names all the fish lol. I just switched the substrate from a rock pebble to sand gravel and rinsed it thoroughly not to get a haze but we now have cloudy water. I’ve read a lot of previous posts about the tank recycling but my concern is if I created a health issue with the fish being in the tank during this process.
Second, I’ve watched some vids on improving the HOB filter by using a sponge on the pick up tube and also taking out the filter pad and using sponge in the filter box, is this something to think about doing? We have a 20 gallon long, nothing big yet.

Hi Dave,

Welcome to the hobby, I am really happy to hear that you are enjoying it! Your aquarium test kit will tell you what is going on inside your tank. If your ammonia and nitrite levels are zero then it’s safe to assume that your tank isn’t cycling and that this is likely sediment.

On the sponge question, I am of the opinion that you can never have too much filtration, it’s essentially the lift support of your tank. Plus, if ever you want to cycle a second tank, adding the used pre-filter can really speed up the process. If your current filter uses those “disposable” cartridges, then you will be considerably better served by swapping out to sponge. I advise using a coarse sponge with a fine sponge behind it (sometimes called filter floss) to trap all the really find sediment particles – it will keep your water crystal clear.

i have 50 gal tank, and cant solve my cloudy yellowish-brown water problem….
no driftwood in tank, no live plants, and..have removed all ornaments and gravel…does not make a difference.
i have about 20 small guppies and goldfish in this tank, average size 1.5 inches…only 2 are over 2 inches….im not over feeding; the ph, ammonia, nitrates, etc.. levels all good….my main filter is rated for upto 75 gal tank and includes carbon media..ive changed it out even though it hasnt looked very bad…and ive recently added a second micro filter/ has made only very minimal improvement….i have tried frequent ater changes…i changed 7 gals per day for 10 consecutive days….slight improvement was only temporary, within a few days it was back to starting point.
ive tried cutting off all light for several days…no efferct.
i havent yet tried a uv light….bur probably will, still….only treating the symptom if that does help…
im almost to the start over from empty tank option…but need to understand what the issue is…
i would greatly appreciate any suggestions you can offer….

Hi Neale,

Only a couple of things spring to mind:

7 gals/50 gall is barely a 10% water change. Try upping this to 50% each day – it doesn’t matter the amount you change, your fish and beneficial bacteria will be fine. If you noticed a slight improvement on the small water changes then back to back big ones may be what is needed. If this solves the issue, from here you would do larger weekly water changes to stay on top of it.

Hi, I’m new to having fish but my water is very cloudy (milky-ish). My parents put a few fish in my tank while I was away (they put the water that the were brought in inside my tank) and when I got home it was cloudy (not as much as it is now). I just recently found out my water filter was not assembled correctly, so I fixed it last night. This morning I woke up to even cloudier water! I’m young and don’t know what to do! Also, I should definitely mention when I had my water tested at Petco yesterday he said my ammonia and nitrites were good but my nitrAtes and ph levels were dangerously high!!!! Please tell me what I need to do so that I can add more fish!!! One last thing, (sorry) I have a 20 gallon tank, live plants, and zebra fish and guppies. Hope that helps (I also followed Petco’s instructions to do a 1/4 water change, and I’ll do a 1/10 water change once a week for two weeks, then I’ll have it tested again). SORRY FOR THE LONG POST BUT I AM DESPERATE!!!

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