Fish Tank Cloudy After Cleaning – Best Method To Fix This Issue

Tank cleaning is essential if you want to keep your fish happy and healthy. That said, not all tanks are pristine after a thorough clean-up. Sometimes, you will still spot splashes of mist getting stuck on the walls, resulting in an ugly and dirty aquarium.

So, what are the reasons behind the fish tank cloudy after cleaning? And what can you do to fix this problem? Find out the answer by scrolling down!

Reasons For Fish Tank Cloudy

overcrowded fish tank

Fish tanks getting cloudy can be traced back to multiple reasons. Below are some of the most common causes.

Accumulation of organic matter

Sometimes, organic matter such as your fish’s waste or food leftovers are left untreated inside the tank. Over a certain period, these organic substances give way to bacteria and fungus, creating excessive cloudiness.

This situation is mostly found in the first few weeks after a tank is set up, leading to its unofficial name of “new tank syndrome.”

Failure to rinse the tank properly

If you notice that your tank gets cloudy after setting up a tank or changing water, chances are you have not cleaned the gravel and filters carefully enough. Dirt, dust, and other types of trash may find their way into the tank’s water, leading to cloudiness.

Changes in water ingredients

When you perform a partial or a full water change, expect to see a bit of cloudiness forming on the tank’s walls. This is mostly due to untreated water. Too many heavy minerals in tap water can be the cause of cloudy walls.

A spike in organic materials

A fish tank can get cloudy even after you clean and refill it. The reason for this phenomenon is that the water flow stirs up the substrate (or gravel, depending on how you design your tank).

Hence, lots of organic materials are misplaced, resulting in a bacterial bloom after the water change.

How To Get Rid Of Cloudy Water In Fish Tank

Once you have determined the cause of the cloudy fish tank, returning your aquarium to its pristine state should not be a problem.

First of all, whether you have a cloudy fish tank from gravel or a cloudy fish tank from water change, the culprit always boils down to excessive organic material. Hence, you are recommended to remove these matters, preventing them from nurturing a bacterial bloom later on.

Anything from fish waste and unfinished food to dead plants and animals must be eliminated.

Make sure to take care of the substrate or gravel as well. Carefully remove it from the tank and eliminate all accumulating trash, debris, organic waste, or dirt. The more dirt-free your tank is, the lower chance it has to develop cloudiness.

Once you have taken care of the bottom, do not forget to pay attention to the filter. Organic matter may end up getting stuck inside the crevices of a filter, so consider using a brush to gently wash away everything. Rinse the filter under running water and dry it thoroughly before re-installing it inside your tank.

Now, you may notice how sudden movements can stir up the water inside, creating more favorable conditions for waste to build up. Thus, it will help if you can be a bit more gentle when it comes to changing water, putting in decor, and installing filters.

Anything that may disturb the tank’s natural state must be avoided at all costs.

How To Avoid Fish Tank Cloudy

Learning how to treat a cloudy fish tank is important. But it is even better if you can take some precautions in the first place.

Control your fish’s diet

Most of the organic matter causing a bacterial bloom comes from your fish waste. The more they are fed, the easier it is for them to excrete.

While you should not starve your fish (unless they need a fasting phase), feeding them constantly is not recommended. Make sure to monitor the quantity of your fish’s diet so that they do not eat more than needed.

Consider the size of your tank

Hosting 6 to 8 fish inside a 10-gallon tank is a disaster, as the waste produced will soon pollute the water and lead to cloudiness. If you want to minimize this problem, do not exceed the number of fish recommended for each tank size.


1. How long does it take for cloudy fish tanks to become normal again?

In most cases, free-flowing bacteria will take around 48 hours to settle on the tank’s floor. After this period, you can expect your aquarium to be clean and pristine again.

Do not try to hasten this process, as any external interventions may worsen the problem.

2. Can dead fish cause cloudy fish tanks?

Yes. If you have a big tank with lots of fish, it is easier to miss when a fish is no longer alive. If left unattended, dead fish can start rotting, causing waste accumulation.

Therefore, you must be attentive and look for any sign of trouble when having a large fish community at home.

3. Can algae cause cloudy fish tanks?


fish and algae

Yes. Algae is organic, which means it is still capable of producing waste. When you let algae grow uncontrolled, chances are your tank will be polluted. If this happens, turn off the light and cover the tank with a thick blanket.

Without direct exposure to light, algae cannot enter its photosynthesis phase. Hence, it ends up starving and dying. As soon as algae are dead, you can scoop it out of the tank.


Having a fish tank cloudy after cleaning is a frequent issue. But you can proactively prevent this from happening should you follow the guidelines above. If you think this article is useful, do not forget to share it with fellow aquarists!