How to Get Rid of White Cloudy Aquarium Water

Cloudy Water

There are a couple of things that could cause white cloudy aquarium water.  The good news is that they are easy to treat once you narrow down the cause.  Dirty substrate or decorations, or a bacteria bloom are the usual suspects.

Dirty Substrate or Decorations

This is very common reason for cloudy aquarium water in newly set up fish tanks.  It is important to thoroughly rinse your aquarium substrate and decorations before putting them in your tank.  If you believe this is the reason for your cloudy fish tank water, there are a couple of things you can do.  Give it a couple of days and you should notice that the particles fall to your fish tanks floor leaving clean water behind.  If this doesn’t happen on its own you should start 20% water changes until your water clears.

Is a Bacteria Bloom the reason For My Cloudy Aquarium Water?

Did you just do a large water change?  Have you just thoroughly cleaned your tank? Have you just medicated you fish? Have you just set up your tank?  All of these things can sometimes cause a bacteria bloom.  If this sounds your situation, you the best advice is to sit back and wait.  When those bacteria establish themselves, your cloudy aquarium water should clear up on its own.

Just Give it Some Time

As you may have noticed the basic treatment for white cloudy aquarium water is to hurry up and wait.  There are chemicals available but they are not recommended.  White cloudy aquarium water will almost always clear up on its own.

Tell us about your experience with white cloudy water.

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48 Responses to How to Get Rid of White Cloudy Aquarium Water

  1. Candace October 14, 2007 at 12:05 pm #

    We bought a new 77gal tank, pre-washed everything, added a couple of dozen gold fish let them sit for a couple of months before we add more expensive fish. Went away for a week the begining of Aug and came home to a total green tank? We changed the water and did all the treatments, water testing etc…it seems within a couple of days the water starts to go cloudy then if we leave it long enough it will go green.
    If you could give us some addvice that would great!

  2. Eric October 15, 2007 at 7:04 am #

    Hello Candace,

    The trick to beating aquarium algae is getting rid of any excess nutrients. This will starve the bacteria and get rid of your algae problem. You can find some tips here . Frequent water changes and a chemical treatment should do the trick over time.

  3. Diane November 15, 2007 at 10:38 am #

    Great, informative site! I have a 10 gal. tank with 13 African Dwarf Frogs and some Mollies and live plants. Everything is fine and dandy UNTIL I do a water change. Then immediately I get white smelly water. The last time this happened I did a 25% water change twice a day because the water got so bad. I had to move the Mollies to another tank because they were dying. Luckily the froggies survived although the water got worse and worse. Finally, I pulled the whole tank apart and washed the substrate, a clay and stone mixture 2″ deep. And planted new plants. That seemed to clear things up. The plants are growing nicely as I have a co2 maker on a timer. I added back some Mollies after a bit and everything has been going along great, no problems, no water changes, for weeks. The other day I was feeling guilty because I read so much about water changes so I changed 20% of the water (with conditioner of course) and rinsed the filter and that very evening the water started to get white and now it is getting smelly again. The Mollies were all at the top, even though a PH strip said everything was within normal ranges. I removed them again to be safe. The water isn’t as smelly as the last time but it looks like it will get worse. It seems like the initial water change throws my tank in turmoil. What am I doing wrong? Thank you so much for your help.

  4. Eric November 15, 2007 at 11:03 pm #

    Hi Diane,
    Sounds like a classic case of a bacteria bloom. What’s happening when you deep clean you tank and filter is that you are removing the good established bacteria that is necessary to keep your aquarium balanced. Drastic water changes, filter replacements, substrate cleanings are all disruptive to your bio filter.

    Take a look here for a little more detail on it. & here

    For now, I would just try to keep your nutrients under control and give it some time. Nutrients just feed the problem. You can also find some products that help control nutrients at your local retailer if you want to speed things up a bit.

  5. APRIL February 8, 2008 at 10:22 pm #

    Thank you so much for this site, Eric! I followed your advice and my tank looked less cloudy IMMEDIATELY!

  6. tinkrbrr February 10, 2008 at 11:00 pm #

    I have an aranda lion head. I saw the plecostomus,s in my tank suckering her side, which caused red circles like blood blisters, but skin not broken. I got rid of the plecos, as they were very big. I treated the tank for 5 days for her sores and she seemed Ok. Now she has 2 big round red sores with canker looking skin around it on the same spot I also have a Koa with her , same size, that has a small orange swollen spot of her side. There are no more fish to harm the others, as I have watched them closely Help, as I have no idea what to do.

  7. Eric February 12, 2008 at 8:04 pm #

    Great to hear April!

  8. Eric February 12, 2008 at 8:13 pm #

    Hi Tinkrbrr,
    The red sores sound like a bacterial infection. Frequent water changes are very helpful in working on the root of the problem. If it won’t clear up on its own after some good maintenance, you can find many antibiotic options at your local retailer. The most popular active ingredient is Tetracycline.

  9. steve February 21, 2008 at 11:06 am #

    I have a 30 gallon tank now after battleing a green tank for a long time the water was crystal clear and now it is starting to get cloudy I did a partial water change. but i also added more fish in to the tankabout a week ago. What should i do to fix this

  10. Eric February 24, 2008 at 2:42 pm #

    Hey Steve,
    You might try some bacteria starter. Depending on how aggressively you worked on clearing up the algae, you may have disrupted the already established good bacteria.

  11. volker February 24, 2008 at 8:01 pm #

    i have a 4 year old 46 gallen tank. i have 3 clown laoches , 3 tiger bards and 2 gromies plus one large alge eater. the water in the tank whent cloudy about 2 weeks ago and i can’t get it to clear. have done 2 water changes. any suggestions?

  12. Eric February 29, 2008 at 3:26 pm #

    Hi Volker,
    If there have been any big changes that may have disrupted the bio-filteration you should add some bacteria starter. Changing the filter, big water changes, and some chemical medications can do this.

  13. chris March 14, 2008 at 2:58 pm #

    I have a 30 gallon tropical community tank with a few danios, some platys, some mollies and a pleco and my water is very cloudy. I have been doing 10% water changes daily as recommended by other sites but my water is still incredibly cloudy. Any suggestions?

  14. Eric March 16, 2008 at 3:32 pm #

    Hello Chris,
    Bacteria blooms usually work themselves out over time once the good bacteria builds back up. I’d suggest bacteria starter to move things along. Also, don’t do anything too disruptive to your bacteria. You’ll want to steer clear of filter changes, big water changes, and medications if possible until it re-establishes itself.

  15. Honus March 17, 2008 at 12:55 am #

    Hi everyone,
    I am a newbie. I just setup my tank about 2 weeks, i have 5 oscar in a 72g tank. the water gets little cloudy. I change it 15% every 2 days. however, i notice some white stuffs on the fish and it seems to do manage the fish fins and tail. the fish act normal, eat, swim around. Do anyone have any idea what problem I have. i want to do the right thing. Thanks.

  16. Eric March 20, 2008 at 8:17 pm #

    Hey Honus,
    The cloudy water is probably caused by the un-established good bacteria. As for the white on the fish, you might be dealing with Ich.
    I wouldn’t react yet with treatments until you see other signs of sickness. If your fish are lively, they probably aren’t stressed. The problem is that the treatments can be harmful the set-up of your tank.

  17. kolby April 5, 2008 at 8:01 pm #

    Hello, i just sat up my tank a week ago and everything is doing really well. But i just noticed yesterday that my water is starting to get cloudy? What should i do?? is it because its a new tank?

  18. Eric April 8, 2008 at 8:44 pm #

    If you are sure it’s white your best course is to just wait it out like described in this post. Take a white cup and dip some out to make sure. Sometimes algae just looks cloudy until you look at it against white. Then you notice the green. If it is green, take a look here . There’s a lot of info.

  19. random dude May 6, 2008 at 8:49 pm #

    i have a 20 litre fish bowl and every time i change the water(20 percent) in the tank the water stays cloudy. I just can’t seem to keep the water clear. Cpuld you help me with my problem. I have 10 3 cm gold fish and one 2 cm mornada. Also how many fish can i hve in my tank per litre

  20. Eric May 7, 2008 at 9:46 pm #

    Take a read through here for fish count. Sound like you are a little heavy.

    To kick the cloudiness you’ll need to ramp up the % change. If you’ve been doing 20%, try 50% every other day, then work on the cause.

  21. Kris May 11, 2008 at 4:33 pm #

    HELLO, ERIC ; D…..

    I am a new owner of two red oscars and I really need guidance on how to maintain my tank and the health of my oscars. My first ? ……Is it ok for the oscars to be in the tank while the tank is cloudy, given that there behavior is normal (swimming, eating, hiding when the lights are on and then coming back out when the lights are off)……

    My second & third?…..Right now I have them in a 10 gal., I know this is not a suitable size tank, but I would like to know is if they will be ok in the 10 gal. tank with cloudy water and constant water changes until I put them in a bigger tank……..and is a 30 gal. good enough for my baby oscars permant home…..

  22. Eric May 13, 2008 at 5:50 am #

    Hey Kris,
    The cloudy water isn’t stressful for your fish. The signs they are showing are also healthy signs.

    Take a look at these posts for Oscar info.

    The 10 gallon will work for a very short time but you should really get them out of there fast. While they are in there make sure do water changes very often. A 55 gallon would be most suitable. There are reports of Oscars getting up to 15in. 30 just isn’t enough room.

  23. brett May 19, 2008 at 3:42 pm #

    Hi Eric I changed the gravel and cleaned the tank with just water did the monthly filter maintenance and I also changed the water then I did another change over the weekend but the water is still cloudy what it has is maybe what looks like to me is little white particles floating around I also had to change the biowheel on one of my filter because it was not turning at all it pretty much stopped for good on saturday. Should I do a another water change. I did about a half tank water change the other day.

  24. brett May 19, 2008 at 7:53 pm #

    hi it’s me again I did another water change today about half maybe a little less but the water does look a little better than it did before I did the change.

  25. Bryan May 20, 2008 at 4:45 pm #

    Hi I used to have a tank that i put my pet turtle in but then he died
    Yesterday I decided to get some fishes and i used the same tank
    I cleaned everything and added prime to the water
    I also added some live plants
    Yesterday the water was ok
    but today the water is starting to get a little bit cloudy from the bottom
    What can i do to stop it from turning cloudy?
    ( I don’t have fish in there yet so yeah the fishes are not the problem)

  26. Eric May 27, 2008 at 5:47 am #

    Hi Brett,
    The thing that worries me the most is the break down of your bio-filter. With the filter and big water changes, and also the gravel cleaning there probably isn’t much left. Given all of that, it sounds like a classic bacteria bloom as described in this post. Make sure you are adding bacteria booster when you are doing your changes and after a little time, it should calm down.

  27. Eric May 27, 2008 at 5:59 am #

    Hey Bryan,
    Has your cloudy problem settled yet? Was anything added like new gravel that could have added particle that just needed to settle?

  28. Bryan May 27, 2008 at 7:37 pm #

    Yeah everything is ok now. I dont know what it was but it just cleard up by its self.

  29. Tarah May 28, 2008 at 4:34 pm #

    Try purchasing a few algie eaters that fixed teh problem for me. Its like having a house cleaner for you fish tank 🙂

  30. Kristen July 17, 2008 at 8:36 pm #

    I am fairly new to the fish tank world. i had one last year, got algae, did an whole tank change becuase i was nervous and my fish died. i spent a year feeling terrible and then finally decided to start again. so i did the whole tank cycle thing before putting fish in and we are going strong. i have 3 silver mollies in a 20 gallon. i have had them for about 2 months and probably haven’t done enough water changes. the water started to get cloudy and now has an odor. i bought a product called Clear Water from Jungle. do you think it’s safe to use or should i just keep cleaning it out and wait? thanks!

  31. Eric July 17, 2008 at 8:45 pm #

    Hi Kristen,
    I would steer clear of the chemicals until you tried some other methods first. Many are tough on you bio-filter. Just start with a 25% change every day or two for a week. If no change, then you can get a little more aggressive.

  32. Brian July 26, 2008 at 8:16 pm #

    I’m stumped. I normally clean my fish tank every 2 weeks. I change the filter and take out the fake plants and decorations to clean the algae from them. I also vacuum the gravel to remove the excess fish food and waste. I have a 10 gallon aquarium with 5 fish. After the cleaning a few weeks ago we had a mysterious outbreak of white slimy strings that attached itself to EVERYTHING in the tank. This is or “was” an established tank until a few weeks ago. My wife experimented to try to find the “root” cause of the problem. First, we removed the decorations and plants and did COMPLETE water change. That may have been a bad idea, you tell me. We went to the pet store and asked the person there what it might be and he said it could be “slime mold” in the tank and that we should bleach everything, replace the gravel, and start over. So, we bleached the decorations and plants. I did not bleach the inside of the tank or do a gravel change because I didn’t want new tank syndrome. I was a little worried to do that. Maybe I should have. Anyway, after bleaching the plants and decorations we added everything back into the tank. After a few hours the white slimy stuff reappeared. So, we removed the fake plants and decorations again, did a partial water change and waited until the next day. The next day the water was clear and looked fine. My wife added the plants back to the tank and again the white slime returned. We removed the plants from the tank and did another partial water change. We waited 1 day and the water returned clear. Then we added the decorations back into the tank and everything was fine after that. I decided that there must have been something on the fake plants that was causing the problem so I went out and bought brand new fake plants for the aquarium. Today, I changed the filter (after 2 weeks), cleaned the decorations, and installed the new fake plants. After several hours, the white slime was back. So, I removed the newly purchased fake plants. After several hours the slime has almost disappeared but the water is milky. The fish don’t seem to be bothered by this but it sure bothers me! Is this just a case of new tank syndrome? Am I cleaning the tank too often or too thoroughly? I’m getting ready to give up on this. Any ideas?

  33. Pam July 27, 2008 at 12:28 pm #

    Eric What advice did you give april about her cloudy water? Could you tell me .I have angle,gromie,and afew other fish Ive had the 65 gal tank set for a while I had an oscer for 2 years he had gotten so big I got rid of him and now I have smaller fish and have seen there is a white cloud there now for about a week . my pet store says my water is fine but it my be a bac bloom how long will this last just did a 10 gal water change today 7-27-o8 should I just wait a bit longer or do you have an idea? Pam

  34. Eric July 28, 2008 at 6:24 am #

    Yeah, I would work on getting your tank re-cycled. It sound like it was wiped out. That is just weird about the fake plants but I would have to think it is more of a coincidence. Although, the number of in and outs with the same results is odd.

    Algae in general is caused by the same thing, including string algae. This is probably a separate problem from the cycling. You’ll want to look for a cause as you cycle your tank again. Take look here

  35. Eric July 29, 2008 at 5:58 am #

    Hi Pam,
    I looked around a little for April’s original post/email and couldn’t find it. Either way, my advice for your situation would be to wait a little longer. Give it a week or two before worrying or making any changes. Also, you might just dip a cupful of water to make sure it’s not actually green. Many times this just looks cloudy depending on your background.

  36. Jackie August 4, 2008 at 9:47 am #

    Help! I can’t keep the water clean in my son’s 10-gal. aquarium. I just did a 60-70% water change and used vinegar (rinsed thoroughly afterwards) to clean plastic plants and decorations of algae. Changed filter, and rinsed bio-filter. For the first few days, everything’s great. Then, the water starts to look brackish again. My son has 2 African cichlids, a green-spotted puffer fish, 2 danios, and an algae-sucker. I’m feeding them very minimally now, because I thought maybe over-feeding was causing the problem. What do I do to keep the water clearer for longer than a couple of days?

  37. Emma August 5, 2008 at 7:27 pm #

    I’m been told that adding some water from a clear-water tank with a well-established bacteria colonies into the cloudy-water tank will help clear the cloudiness. Does this work and is it safe for the fish? My second tank is clean. It’s not treated for anything and the fish in there are very healthy. Is it ok to add water from the 2nd tank to the cloudy tank? thanks

  38. Eric August 10, 2008 at 9:28 pm #

    Hi Jackie,
    Some great algae fighting tips are over here.

    You have to find the root. Here are the biggies. Overfeeding, sunlight, high heat, or dirty tank from high nitrates. While working on those, 50% water changes every couple of days should keep it in check. After a couple weeks of that and getting rid of the cause will clear your tank for good.

  39. Eric August 12, 2008 at 6:25 am #

    Yeah, it sure is. The key isn’t really using clear water but rather using established water that has some good bacteria set up.

  40. Jeff Snedden April 7, 2009 at 5:59 pm #

    Need a little advice here, we have a 30 gallon tank that we started back around December. I probably didnt conduct enough due dillegence before getting into this, so originally we set the tank up, let it sit for 2 days, then added a few fish. The water was cloudy for a while, and to be honest it never actually cleared up. The fish lived with no problem for mnths. I did water changes, added the conditioner and checked the PH, Ammonia, etc. daily. The water was always healthy, and the fish were too. We added a few more fish, including catfish and a pleco, and still the water was hazy, but healthy.

    On Saturday I vaccumed the gravel and did a 50% water change. Again following all protocol. Everything was fine. Sunday morning, went to feed the fish around 0900am, and they were fine. Went back to the tank at noon, the water was totally white and all our fish had died in the span of 3 hours. This was heartbreaking, and I was going to simply give up. The only fish that survived were our 2 catfish. Because of them, I decided to start over. I cleaned the entire tank out, bought new interior stuff, gravel, filter. I scrubbed the entire tank with the Fish Tank cleaner kit sold at Petsmart. I spent $200 to reset this tank. I cleaned all gravel and plants beforehand, and the water was perfect PH, ammonia free and clear as can be when I added the 2 catfish. They seem happy and healthy, even with the stress of the moving, etc. Now the water is slightly cloudy again, roughly 48 hours later. I am very dillegent on testing the levels. Should I wait and let it settle? For how long? I have tried the water clear stuff in the past and found it to make things worse. I just don’t want to cause the death of any more fish.

    Any advice would be great, thanks.


  41. Eric April 8, 2009 at 6:36 am #

    Sorry to hear about your fish loss and trouble. Don’t worry, we’ll get your tank back in shape. Not sure if you’re testing for Nitrates and Nitrates but if not, you’ll want to get yourself some multi test strips. It sounds like a cycling problem. Take a read over here.
    Ammonia isn’t the only problem that comes from the cycling process. Nitrites can be very harmful for fish as well. Nitrates are usually the source of bacteria growth. Ammonia is the most widely used indicator of water health, but there are a few other indicators that help give you the full picture. Since it’s been 48hrs since setup, I don’t really think it’s debris that going to settle.

    Next steps: Get some bacteria starter to add with your water changes. Make sure you are not overfeeding. Less is better than more as you get through this process. Monitor Nitrites and Nitrates. The cycling post addresses how to deal with spikes in these but basically it’s by quickly doing water changes when things are at harmful levels.

    I know it can be frustrating. Stick with it. It’s a fun hobby when things aren’t going bad. Getting started, there really is a lot of learning.

  42. Nancy Smith January 3, 2011 at 8:48 pm #

    Well i had my tank very cloudy and i used a spray to clear it up and it worked very well and only for ablut $4 it can’t be beat for my tank. I don”t know why it didn’t work for your tank. And sorryto hear about the loss of your fish i bought a bunch of fish before i cycled the tank and i wasted about $20 so i’ve been through the same thing. I know it’s agervating but once you get your tank healthy it is so awesome! Hope this helps you.

  43. Martin Parks June 24, 2011 at 2:13 am #

    I have a white bloom in my tank how long should i wait for it to go away? and is it going to hurt my fish?( silver arrowwana ) and oscars. my local fish store sold me products that dont work and told me to do 25% water change and it was worse the next day!! please help:)

  44. Eric June 29, 2011 at 6:09 am #

    Hi Martin – Don’t worry, it wont hurt your fish. There are a lot of factors that relate to the time it takes. If you get aggressive with your water changes you’ll get ahead of it, 25% or so for 3-4 days in a row. Starter bacteria will help as well with each change.

  45. melissa July 14, 2011 at 3:00 pm #

    Hi Eric, I have just set-up a new 55 gal tank, I prewashed all of my pebble rock before adding to avoid additional dirt and debris in the tank, I cleaned the plants (just scrubbed them off and hosed them off) before adding to the tank filled the tank and it has now been filtering for 3 days. Although very anxious to add angel fish I have postponed doing that till my tank clears up, it is a white color not bad but deffinately not clear outside of the chemical to remove the chlorene I have not added anything else. Is this normal and how long will it take to clear up, and how long should I wait to add my angels? Thanks, Melissa

  46. Eric July 15, 2011 at 5:36 am #

    Hey Melissa – You should see it calm down shortly. Starter bacteria will help move things along for you since you’re anxious. Angels are touchy. If you’re able to, I’d wait to add them until you get your water clear.

  47. Ian July 23, 2011 at 11:02 am #

    I have a 20 gallon tank with a black moor goldfish, a goldfish,two white tetras, and a dinosaur bachir. I have just switched my fish over to this tank about 2 weeks ago, and it went from green, which i fixed with closing my blinds, to white cloudy water.If it helps, i use an undergravel filter, but to do the quick clear I used my power carbon filter, and that seems to clear the tank up, for a little at least.

  48. Bob August 24, 2011 at 4:17 pm #

    Dear friend,

    I set up an 80 gal tank, and put like 5 gold fish and 3 kois, but i still have white cludy water but i’m going to put another filter because my filter is only up to 50 gal tank, probably that’s the problem I hope,