Why is My Fish Tank Cloudy?

Why is your fish tank cloudy? The cloudiness in the aquarium probably happens for several reasons. One of them is overfeeding. When you continuously feed your fish before they can consume within one to two minutes, the uneaten food can decompose and allow cloudy water in the tank. Overstocking or too many fish in the small tank can also cause cloudy water. 

Uneaten food in the aquarium can build up excessive amounts of ammonia and nitrates that encourage cloudiness. So it’s important to be careful when feeding the aquarium creatures.

Fortunately, The large fish tank comparatively becomes less cloudy. You can keep 1 gallon of water for one inch of tropical fish. To goldfish, hold three gallons of water per inch of fish.

To get rid of the aquarium cloudiness, it is always best to start with a big tank you can afford. The bigger the aquarium, the more waste it can handle before converting the cloudiness of any problem to your fish.

There is another big reason for getting a tank cloudy is called new tank syndrome. When you set up a new tank or perform a complete water change in your existing aquarium, it is normal to become your tank muddied. It is part of the normal biological cycle. It happens for movement in the nitrogen cycle and releases the gases, then the ultimate result is increasing water temperature. By 50% percent of water changes, you can start the normal cycle again.

Make sure you are regularly changing and cleaning the filter cartridge. It is best practice to change your filter cartridge once a month if you have a normal bioload. 

If you have a heavy bioload or you are petting fishes that produce comparatively more waste, changing the filter cartridge twice a month is a secure option. Especially if you have goldfish or chichils as they produce more waste than other fish.

The possible reasons why your fish tank is cloudy

The issue of cloudy water can be a frustrating situation for many aquarium owners. Unfortunately, there is no single answer or solution to why your fish tank is cloudy because it can happen for many reasons.

Gravel Residue

If the water is cloudy within an hour or two after filling the tank, it’s likely due to a lack of gravel cleaning. The gravel is probably insufficiently washed or has waste. Draining the tank and rinsing the gravel again can get rid of this problem. Clean and rinse the gravel until the water runs clear should resolve the trouble.

Dissolved Components

If the cloudiness remains after cleaning the gravel residue, the most likely cause of the cloudiness is Dissolved organic components such as phosphates, heavy metals, or silicates. Now, the pH level you will find high if you test the water. In this situation, treating the water with a conditioner often solves the cloudiness problem. Besides, you can use RO (Reverse Osmosis) water as it benefits beyond fixing the cloudy water. The RO (Reverse Osmosis) water you may find in the local pet store.

Bacterial Blossom

Cloudy water doesn’t happen instantly after the aquarium is set up. It happens days, weeks, and even months later due to bacterial bloom. It goes through an initial biological cycle that is not unusual becoming water cloudy or at least hazy as a new tank. It can take weeks to months to remove waste from the tank and create bacterial colonies. After completing bacterial colonies, the cloudiness will resolve itself. Decaying plants and uneaten food can cause milky water, which looks in bacterial bloom

However, you don’t need to be panicked over bacterial blooms as they can be resolved by aquarium cleaning. Keeping the aquarium clean by eliminating debris, uneaten food, gravel, and partial water changes can quickly resolve the bacterial bloom. Suppose there are still particles of debris available in the aquarium that you are unable to clean via partial water changes or vacuuming. In that case, you can use a flocculant to clear them away. The Flocculates can clump together the particles of debris so the filter can easily remove them. However, make sure the filter is clean enough to work efficiently. 

Flocculates is known as a water clarifier and may be found in a fish shop.

Green Water

Green water in the aquarium causes excessive algae growth. It is tough to get rid of when you can’t understand the source of them. But if you know the source and cause, it’s easier to cure.

Too Much Light

Too much light is the cause of green water; however, it is easy to cure and prevent. Keeping the aquarium away from the direct sunlight and the light too short will give you the solution of the green water. Try to reduce the time of turning on the light and keep the aquarium out of the direct sunlight.

Excessive Nutrients

Nutrients such as phosphates and nitrates encourage algae growth and must be reduced effectively to resist the algae. A partial water change can give an immediate solution but can’t solve the cloudy green water completely. You should deal with phosphates and nitrates from their sources. 


In the aquarium, phosphate comes from two sources that are decaying matter, uneaten food, and the water itself. Regular testing of the water lets you know the phosphate level of the water. And can understand if it is harmful to your fish. If your aquarium water is naturally increasing the phosphate level, you should use RO water or a phosphate remover to treat the water. You can feed your fish in less amount, and changing the brand can reduce the problem.


Naturally, nitrates are created from byproducts of fish wastes over time. The only effective way to remove nitrates from the tank is partial water changes. When you want to solve the cloudy fish tank, make sure your filter is clean and is the proper size for your tank. Also, be sure you don’t overstock your aquarium.

It is proven that most of the aquarium owners who face cloudy water get rid of it by changing 10 to 15 percent of water weekly, keeping the gravel clean, and using quality food.

Click to read more: How to Clean a Fish Tank?

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