The water in a turtle’s tank may become murky for a variety of reasons.  We will discuss the potential causes of a cloudy tank, how to fix cloudiness, and prevent it in the future.

In this guide, you’ll learn:

  • What causes a cloudy turtle tank?
  • How to fix cloudy turtle tank water
  • How to prevent cloudy water in the future
Featured image showing turtle swimming in cloudy water

Turtles are generally very messy compared to other reptiles, therefore there can be a variety of different reasons for a cloudy tank. Many assume the sure way to fix a cloudy turtle tank is to replace the water however, this may sometimes hinder rather than help the water quality.  

What Causes A Cloudy Turtle Tank?

The three most common causes of a cloudy turtle tank:

  1. Bacteria
  2. Poor tank maintenance
  3. Dirty tank filter


The number one cause of cloudiness in a turtle’s aquarium is actually fairly simple. The odds are that if your tank is experiencing a haziness in the water, it was recently set up within the past week or two. The water you likely added to the turtle tank is clean, bacteria-free fresh water. 

In our turtle tanks, we are attempting to recreate a small piece of nature indoors and try to keep things as natural as possible. In the wild, turtle waste is broken down by millions of bacteria. These beneficial bacteria work to break down the ammonia produced from turtle waste into less harmful nitrite, and finally nitrate. This process is known as the nitrogen cycle. These nitrates are then absorbed by plants and filtered from the water. In captivity, we also rely on using the nitrogen cycle to convert turtle waste from ammonia to nitrates.  These nitrates are then removed from the water through water changes or by using live plants in the tank (or better yet, a combination of the two). 

In a newly set up turtle tank, bacteria have not had a chance to colonize or begin reproducing yet. After a few days, when your turtle begins to produce waste, the bacteria will begin to reproduce and reach a sustainable number to convert the waste to nitrates.  This huge bloom in bacteria will appear as “cloudiness” in the water. Essentially, cloudy water is simply bacteria attempting to break down waste in the water.  

Poor Tank Maintenance

If, for some reason,  your turtle setup has already been set up for a long period of time and you begin suddenly experiencing cloudy water, there may be something wrong with your maintenance of the tank. 

Aquatic turtles are extremely messy creatures that not only produce a huge amount of waste, but they also make a mess while eating.  Many people feeding their turtles in the tank risk creating a total mess every time they feed.  Even if using pellets, which are less messy than other food items, the turtle may still rip apart, chew, spit out, and generally produce clouds of food that become particulate matter floating around your tank.

📚 Read More >> Best Turtle Food For Red-Eared Sliders

Feeding your turtle inside of its tank is something that can very easily contribute to not only a cloudy tank, but it can also produce a foul-smelling odor and the water may appear to have a film at the surface.  This is likely a protein buildup from the uneaten or digested food that you have given to your turtle.  The water quality can quickly deteriorate and this cloudy water can irritate your turtle’s eyes and lead to health problems.   

Dirty Tank Filter

The final potential cause of cloudy water in your turtle tank is that you may not be cleaning out the filter at all, not enough, or it is possible you are cleaning it too well. 


Clean turtle tank filters bi-weekly (twice per month).

Not cleaning your filter at least monthly (but preferably bi-weekly) may cause a buildup of waste and other organic material.  This waste will sit in your filter and rot, which can fuel algae and a foul odor, as well as cloudy water. 

The filter will begin pushing out waste that it is supposed to contain if it becomes overrun and overcapacity with the waste it can handle. This will most certainly lead to cloudy water and issues in the tank. 

If you do clean your turtle filter and still experience cloudy water, consider how often the filter is cleaned.  If it is cleaned very infrequently, consider increasing the number of times it is properly flushed out. 

Bacteria breaking down ammonia during the nitrogen cycle live inside of your filter. If you take out the substrate or media that is supposed to help the production of these bacteria and wash it with tap water, it could kill these bacteria and wash them away. Bacteria building media will likely look like small pieces of plastic or ceramic rings, but come in a variety of forms. By removing the bacteria your turtle tank has worked and spent so much time to establish, you essentially restart the nitrogen cycle and need to build the bacteria colony back up. The bloom from this will then contribute to cloudy water. 

How To Fix Cloudy Water In Your Turtle Tank

  1. Don’t do anything, just wait! If you recently changed your water or set up a new tank, it could be related to bacteria.
  2. Prevent messes during feeding by feeding turtles outside of their tank.
  3. Clean your tank filter properly and on time.

Solution 1: Did you recently set up your tank? Then just wait!

If you have identified the cause of cloudy water to be bacteria-related and you have a newly set up turtle tank, good news!  The fix to this is to simply wait. 


Leave the turtle tank to establish. Over the course of a few days, perhaps even weeks, the tank will fix itself and reward your patience with crystal clear water!

You must allow plenty of time for your bacteria colony to establish and build up. It will need time to grow and handle the bioload produced by your turtle. 

The tank essentially suffers from “New Tank Syndrome”, in which the biochemical properties of your tank have not been established. There are a variety of different chemical processes, beneficial bacterial colonization, and cycles that your tank needs to undergo before it becomes “established”. 

An established turtle tank will have things balanced, with the proper number of bacteria to convert the harmful ammonia and waste into safer to build up nitrate levels. This nitrate can then be removed by water changes once your tank has established and when it registers in dangerous quantities on a water quality test kit. 

In the beginning, however, changing the water is the opposite of what you want to do.  Changing the water every time it gets cloudy will restart the cycle, and it is guaranteed to get cloudy again within a few days. You must allow proper time for the bacteria to colonize and build-up, likely in your filter and other surfaces it finds habitable. 

Once the beneficial bacteria has had sufficient time to establish itself, the water will very quickly, likely overnight, turn clear. Once clear, so long as you keep up with future water changes and filter cleanings, it should stay clear. 

Solution 2: Correct Poor Tank Conditions Caused By Feeding

Feeding inside your turtle’s tank can quickly deteriorate the water quality and lead to cloudy and dirty water.  Not only is this unsightly and potentially foul-smelling, but this can also lead to fungal issues and infections in your turtle, and quickly lead to a variety of potential health problems. 

Most commercial turtle diets are full of nutrients, and can therefore break apart and quickly pollute the water your turtle is swimming in. If you decide to continue feeding in the enclosure, upgrading filters to handle the extra waste and bioload may help to increase water quality and keep the water clear. 


Feed turtles outside of their enclosure to keep tank water clean and prevent potential health problems.

There are ways to avoid this and ensure your water stays as clean as possible without upgrading filters though!  Feeding outside of the enclosure is a sure way to prevent extra food and waste from entering the habitat your turtle lives in.  It will extend the time between water changes and filter cleanings, and will contribute to a cleaner turtle tank overall!  

How To Feed Turtles Outside Of Their Tank

1Take a small container roughly twice the size of your turtle, and fill about halfway with water from your turtle’s tank. Make sure your turtle can’t climb out or they will!
2Add the food you would normally feed your turtle to the feeding tub.
3Wait about 10 minutes, or until your turtle is ready to be removed and has eaten its fill. Remove them from the feeding tub. Place them back in the tank.
4Dispose of the water either outdoors or down a drain, and rinse the feeding tub.  Store it wherever you normally keep it.

Solution 3: Clean Your Filter

The solution for not cleaning your filter frequently enough is to clean it more often!  Many people go based on a weekly or bi-weekly schedule, which is a good rule of thumb.

Generally, it is safe to clean the filter bi-weekly, or whenever you notice that the media is filled with debris and waste. Filters are only there to catch the material floating in the water and keep the water clear. 

Filters also ensure proper flow and assist in biochemical processes to break down waste into less harmful products. Despite this, it is still up to you to physically remove the waste and debris that build up. Removing the physical waste will decrease the cloudiness of the water and increase clarity! A water change will remove the chemical components (nitrates) in the water that you cannot see, but will still help to keep the water clear. The process of cleaning the filter will vary depending on the type of filter you have however, there is a general process to follow. 

How to clean your tank filter

1Remove the filter from the tank if it is submersible (canister filters will have a different media removal process)
2Take the filter to either a sink or outdoors to be washed.
3Remove the filter media. Make sure you keep the biological media, acting as biological filtration, in a small bucket of turtle tank water to keep the bacteria alive and avoid having to cycle the tank over again!
4Rinse freshwater through the filter media to remove a majority of the turtle waste and debris until it begins to run clear.  You may also entirely replace the media if you so choose.
5Return the media to the filter and re-assemble.
6Return the filter to the tank and power on! 

How To Prevent Cloudy Water In The Future

Maintain a filter maintenance schedule

Make sure you clean out your filter regularly to ensure the water quality stays high and to prevent cloudy water in the future! When doing so, make sure you do not rinse your bacteria or media that houses the bacteria with tap water, as it can kill them. This will force the bacteria to restart and have to repopulate the filter, taking time and this could lead to another cloudiness bloom. If you keep the biological media in the tank or in turtle tank water, it will keep them alive while you clean the mechanical filtration designed to remove physical matter from the water.

Feed turtles in a separate container

Feeding your turtle in a separate enclosure and in a designated feeding tub will drastically reduce the amount of maintenance required. It will also ensure that the water quality stays pristine and should not get a chance to become cloudy. With high water quality and good water chemistry, the ecosystem inside of your turtle tank should stay balanced and prevent an imbalance that would cause cloudiness of the water or algae blooms.  These bacteria will also effectively break down waste and can handle higher bioloads, which gives you the option to add a few bio-load light fish such as guppies or mollies.

Use a gravel vacuum to clear debris

If you keep gravel in your turtle enclosure, make sure you use a gravel vacuum to suck up any debris that may be trapped underneath them. Gravel and the use of pebbles in a turtle tank can cause waste to build up and be unable to be pulled by the filter. Using a siphon or gravel vacuum will not only change the water in your tank but pull directly from the gravel all of the waste and material that has accumulated underneath it. This waste has the potential to break down and diminish water quality. Not only can it cause cloudy water, but poor water quality can contribute to a variety of health issues in turtles. 

Aqueon Siphon Vacuum Gravel Cleaner

Why Do Turtle’s Need Clean Tank Water?

Turtles need high water quality because a majority of the habitats they come from have high water quality. This means that the water must be free of ammonia, and have limited amounts of nitrates (detectable by a water testing kit). 

Using a filter to remove waste from the tank is one of the keys to maintaining high water quality. The more powerful the filter, the better off you will be and less maintenance will be required on the tank. 

Poor water quality can lead to a lot of problems in turtles. Puffy eyes are indicative of an eye infection, and respiratory infections can come from cold and particularly unclean water. Shell rot and pits in the shell can also come from bad water quality and a dirty turtle tank.  

How Often Should I Clean My Turtle’s Tank?

A turtle’s tank should be cleaned at least monthly, depending on the strength of your filter, but more often for those that may get filled with debris easily. 

The turtle tank itself won’t need to be completely drained and cleaned. However, if the sides begin to get algae, use an algae scrubber to rub the algae off. 

Then, change 25% of the water or so to remove the algae you’ve sent into the water column. Regular partial water changes and vacuuming of gravel, if you have it, will negate the need to completely empty and clean a turtle or fish tank. Water changes, filter cleanings, and gravel siphoning will be more than sufficient to keep a turtle tank clean, especially if you feed in a separate enclosure!


Is cloudy water bad for turtles?

No, cloudy water is not necessarily harmful to turtles. It is most often an indicator of a bacterial bloom that will fix itself over time. The tank is simply balancing and the biochemical processes must work themselves out to process the waste and material produced by your turtle or fish.

How long does it take for a cloudy tank to clear up?

In a turtle tank, it should take anywhere from a few days to a week or two for the tank to clear up from the cloudiness. Patience and not changing the water are key to ensuring the tank becomes clear!  

Why does my tank look cloudy?

The cloudiness from your tank comes from waterborne bacteria that are establishing themselves in response to the presence of waste from your turtle. Over time they will colonize your filter and break down waste into less harmful products to be removed during water changes.

Dan Roselli

Dan Roselli

Dan has raised, cared for, and rehabilitated turtles for over 10 years. His most recent turtle project involves two rare spotless white Ornate Diamondback terrapins!

14 thoughts on “How To Fix Cloudy Turtle Tank Water”

  1. I cleaned my tank, and all the rocks, pebbles and rocks backings. All cleaned, I replace the rocks and all, but when the water splashes from the filter, I used squeegee to clear the drops, but the there is a film left on the sides. How do I keep these sides clean without looking dirty. I wabpnt to keep the sides clean. Don’t know what to do. Please give me some suggestions.
    Thank you for all your help.
    Is there something for use to keep the insides clean.

    • Honestly, I think the only thing you can do to reduce splashing is to raise the water level or be diligent about cleaning the glass with a damp paper towel or something.

      Unfortunately, there is no real cure-all for that particular problem.

      Sorry I couldn’t help more!

  2. Dan,
    Thanks for posting this article. We have had a maps turtle for 21 years. He is 8 1/2 inches long and feeds on pellets, hand fed no less. We recently moved him to a 40 gallon tank and run 2 – TopFin 70 filters. We also have 14 goldfish in the tank with him. The goldfish constantly nibble at his shell and flesh. The water remains clear but has a constant brownish color, so it doesn’t look clean. I replace the filter media regularly, use TopFin Water Conditioner to remove tap water chemicals and TopFin Biological Cleaner to help breakdown waste. I also replace 25% every three weeks. From your article, I am now suspecting I’m messing with the water too much?? Your comments and thoughts would be much appreciated.

    • 14 goldfish is quite a few for a 40-gallon tank plus a turtle!

      I would recommend finding someone with a pond to re-home the goldfish and only keep a few or to rehome them all and replace them with feeder guppies, which have a much lower bioload. That, or consider upgrading the tank.

      The brownish water is likely due to the heavy amount of bioload in the tank (waste from the turtle and all of the fish). I would almost argue the water isn’t changed enough actually.

      I hope this helps!

  3. We’ve had 2 red eared sliders for about 4 years now and the tank has just started getting cloudy. We keep around 30 gal of water in it and clean it about every 2 to 3 weeks. We feed them in the tank and have never had this problem except for a few hours after cleaning, never lasting more then a day and not that often.
    Appreciate any help

    • Hey Rusty,

      For two Red Ear sliders in 30 gallons, I’d say they’re a bit limited on space there.

      My number 1 suggestion would be to upgrade enclosures. Although they haven’t had issues up until this point, increasing the amount of space they have usually fixes a large number of issues, including the one you mentioned. Cloudy water is often indicative of a bacteria bloom, which can be caused by an increase of nutrients, a new tank, or either cleaning too often or too little.

      I would say that the tank should be cleaned a bit more often, or at least the water changed more frequently. Also, consider feeding in a separate enclosure to lighten the load on the filter!

      Hope this helps.


  4. Hi Dan:
    I have a 100 gallon aquariun filled to 70% and home to two large red ear sliders. Cleaning canister filters are quite a chore for me. Two (Filstar XP series) have started leaking. What are your thoughts of using large box filters? They should be easier to clean and I would be more inclined to do it regularly.

    • Hi Woody,

      I would suggest saving up and consolidating into one larger filter rather than dealing with two.

      The Fluval FX series of canister filters work really well. You would likely want an fx5 or fx6 for sure! If those options are too pricey, I would suggest looking into building your own filter if you’re crafty enough.

      A 5-gallon bucket and be turned into a fairly effective filter, so long as the pump used to operate it is large enough (300gph or preferable more). You could buy new or check Craigslist, eBay, and FB Marketplace. Harbor Freight sells them too.

      So long as the filter has an area for biological filtration (gravel or lava rocks) and plenty of media (100% polyester works incredibly well), you should have beautifully clean water! I hope this helps. Plenty of people have builds on YouTube as well.


  5. Thank for all this terrific information. So I found your article several weeks ago, about a week after I had changed all the water in my red earred slider tank. So I waited as you instructed. It’s now been 5 weeks since I’ve changed his water. Should I be waiting longer or is there something else that’s wrong. I also changed his filter every other week. Thanks again!

    • Hey Jan,

      So water changes I would argue are actually more important than cleaning out and replacing your filter. Water changes should be done weekly or biweekly depending on your nitrate levels (water changes are done to remove nitrates from the water).

      If you don’t know your nitrate levels, consider getting a water test kit, otherwise while waiting for the tank to cycle, you’re not exactly sure when it’s done and taking a shot in the dark. I would replace the water 20% every week or so to be safe (though initially, I would change 50-75% now that it’s been 5 weeks). The water changes won’t eliminate your bacteria, cleaning the biological part of your filter (this is usually a plastic piece or rocks or something) will (but NOT the sponge part that catches the waste and material, that can be rinsed problem-free!).

      Hope this helped!

  6. Dan, we’ve got a map turtle that we’ve had for about a year, she’s about 3″ around and we recently upgraded her to a 40 gal tank with cleaned sand from the creek that she came from (spent several hours filtering the sand before it went in the tank) we’ve since added 3 crawdads, they’re all about average size, between 1″-3″ anyway, the tank has been established for about a month now and I can’t get rid of the cloud, I found out the filter was too small for the tank so I upgraded to a submerged one, also added water conditioner tabs about a week ago, and some tetra tap water safe solution and tetra water clarifier. These were all added about a week ago and the new filter was 2 days ago, do I just need to wait or should I start over with fresh water and fresh treatment? It was established for about 3 weeks before any treatment was used and a month before a large enough filter was put in.

    • Hey there! I would leave everything to settle. It sounds like it will just take a little time for the bacteria to re-establish in the new filter that you have. I would be patient, and if you’re concerned you can change 10-20% of the water every week or so. My best advice though is simply leave things! It should clear up within 3 weeks.

  7. Hi, I recently got a baby yellow belly slider. I just finished setting up the tank and it has just spent its first few days in the tank. But the water is cloudy, and I know I’m supposed to wait it out but it seems to be getting worse. I was wondering if this is normal or if I should try to rebuild the whole tank.

    • Hey there! You can do partial water changes of around 10-20% per week, but do not clean the filter and try to wait things out! It can take up to a month for things to cycle properly.



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Dan Roselli

Dan Roselli

Dan has raised, cared for, and rehabilitated turtles for over 10 years. His most recent turtle project involves two rare spotless white Ornate Diamondback terrapins!

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