Cloudy Water in Aquarium: Causes and Prevention

Cloudy water is very common in the aquarium. There is not a single reason for the water to get cloudy; it can happen due to various reasons. Based on the circumstance and color of the cloud in the water, we can find out the causes. 

The water can get gray or milky white, yellowish, or even green. Seeing cloudy water people always come to the conclusion that it is wrong and harmful, but cloudy water always doesn’t mean that it is harmful. But sure it doesn’t look attractive. some easy and proven ideas will help you to get your water clean. Here we will discuss the causes, treatment, and prevention measures to the cloudy water.

Why is my Tank Cloudy?

Not only overused old tanks have cloudy problems, but also new tanks have this problem. If the tank gets cloudy within an hour or two, then the reason is unclean gravel and substrate in the tank. Rinse the gravel in clean water until the water comes clean that will solve the cloudy problem. 

But if the tank gets cloudy after some days, then the case is something more complicated than the gravel for sure. A new tank is in the blank state, and there is no life form present in the tank. Once the container is introduced with water, fish, and foods, the bacteria and microbes present in the water start to feed off them and start to multiply and create these clouds in the water. 

This is due to introducing a lot of fish in the beginning. More fish means more food and more waste, which provides these bacterias and microbes more supplies to survive on.

Types of Cloudy Water

There are several causes of cloudy water in the tank. According to the situation and color of water, we can conclude what the cause of the problem is. So without wasting a little time let’s dig into the types of cloudy water that can occur in the tank:-

  • White or Grayish Water
  • Green Water
  • Yellow or brown cloudy water

Each color of water denote different cause and problem and have a different approach to get rid of them. These are the most common problems faced in the tank. Let’s discuss them in brief below down.

Gray/White Cloudy Water

Cloudy Water

White/grayish water in the tank seems like someone has just poured a glass of milk or mixed flour in the water. Usually, the water is transparent but has a blurry sight due to the smoke like a white cloud. A severe case of this problem has resulted in zero viewing sight making it impossible to see anything. Let’s discuss the causes of gray/white cloudy water.


We have to be careful while introducing a new substrate in the aquarium. Introducing properly not cleaned new gravel, soil, and sand in the tank release dust particles in the tank that works as the formation of the smoke particles in the water. Or after coming into contact with water and other substrates rubbing breaks off tiny particles of the gravel and produces fine dust particles that roam around the water freely, contributing to the formation of the cloudy water.

Treatment and prevention

One way to deal with the cloudy water formed by the new substrate is to leave the water steady and wait to naturally clear. This might take a few hours to the day, depending on the dust and smoke present in the water. For faster results, we can change 50% water in the aquarium or the most effective one:- You use the water filter for fast and best results.

Cleaning the gravel properly before introducing it in the tank could prevent this problem from happening. Putting the water slowly into the tank is also one of the techniques to not get cloudy water.

Green Water

Green Water

Green Water is also one of the most common problems in the tank because it is the condition of an algae bloom, unlike other algae, these algae float free in the water. 

Algae bloom happens very easily and fast under thin conditions. The water turns into bright green and becomes hard to see in the aquarium. 

These algae blooms don’t harm the fish directly, but once the problems go deep and the blooms are rapid, it can create additional issues and invite new contaminations in the tank. The perfect condition for the algae to bloom is to get direct sunlight and food in the form of nitrogen.

The conditions that are best for the algae to grow and revive is are given below :

Nitrate Level

A high nitrate level is not good for the fish in the aquarium. The nitrate levels should be controlled to the point where it’s not a harm to the fish. The major cause of high Nitrate level is:


In the name of care, people often tend to overfeed the fish. Overfeeding the fish causes a lot of leftovers in the tank that produces nitrates in high amount. 

The fishes should be fed in a very controlled manner, not much, not less. Expert suggest that you should give your fish only those amounts of foods that the fish can eat in about 30 minutes, not more than that.


Maintenance of the tank mainly suggests cleaning the water and installation of proper filtration. These tasks reduce the chance of algae blooming in the tank.


lights are great in an aquarium to enhance the beauty of it. Some fish required lighting to be compulsory, and some don’t require it, but it will be great to look.

 Leaving the lights on for too long or using intense light will result in the algae growing inside the tank. It’s always better to control the light timing in the tank.

 For cold-water fish, I recommend you to turn off the light during day time as their natural living lighting condition matches the daylight.

The fish shouldn’t be kept in direct contact with the sunlight that will heat the temperature of the aquarium, and it provides a great condition for the algae to survive and grow.

Controlling the light helps to eliminate the green cloud from the tank. If you want to keep the lights, reduce the light time, or completely disable them until the water becomes normal, and you can slowly start increasing the time.


Phosphates found in the aquarium are the remaining off of the foods, waste plants organism, and dead fish. They are the great nutrients for the algae to grow from.

The best way to control phosphates in your aquarium is to not overfeed the fish, clean the tank properly and timely, change the water at least a week, remove dead fish, and unnecessary things from the tank immediately.

Yellow or Brown Cloudy Water

This problem starts as a yellow tingle, but if not done anything about it, water will darken the color will look like the cow urine. 

The pleasant view of the aquarium will be destroyed and will look like some chemical mixture in a lab.

The likely causes of this problem are the driftwood, leaves, and seeds in the aquarium. The woods and stuff leak the brown color into the water and make the dark water brown.

Some aquarium enthusiasts people like the brown color to their water so, they intentionally design the driftwood to darken the water. These aquaria are called “Blackwater aquarium.”

The tannins released from the driftwoods depends on the type of woods, some woods like manzanita doesn’t release the color into the aquarium, but woods like Malaysian driftwood leaves the shade of light brown.

The tannins can be pre-released by soaking into the water, and if you want to complete the process faster, soak into the warm water.

If the aquarium is already colored brown, then the use of carbon filter will be the best thing to do, the carbon filter will clear your tank and leave crystal clear water.

How to Prevent the Cloudy Water Tank

Getting into all those pieces of information above, you have figured out by now that no tank turns cloudy in a blink like magic. It’s a long process that can be reduced and even prevented. The primary preventive steps are as follows:

Don’t overfeed your fish

The greatest fear of the fish keeper, in the beginning, is that they may starve the fish to death. But they fail to see the total picture that other bacterias and microbes may benefit the over nutrition present in the water. The cloudy bacteria take advantage of the situation and grow in numbers.

Due to the overfeeding nitrate and ammonia level can also increase in the water. This condition will be worse to happen in the aquarium.

Fishes in natural conditions maybe eat daily; some predator fishes only eat once a week or twice a week. Every fish can survive three days without food.

Don’t crowd out the tank

Keeping more fish in the tank is always a bad idea. It’s always recommended to keep less fish than the capacity of the tank.

More fish means more waste and more foods & nutrients for the bacterias and microbes. You don’t want that to happen inside the aquarium.

Some fish are territorial and fight other fish for territory. These fish require more space inside the tank. Keeping ferocious fish in large numbers in confined space is not a great idea because they tend to quarrel and get injured and spread contamination.

Test aquarium water

Testing is always a better idea than leave untested. Testing water for the ammonia and nitrate as soon as it gets cloudy could help to minimize the damage that could happen. 

Filteraization is the compulsion to keep your tank and water in perfect condition. Using a carbon filter to clean and change your water helps the tank to not get cloudy. Carbon filters absorb the remaining foods, organisms, dead fish, and other remaining unnecessary stuff.

Bacterial Bloom

Bacterial Bloom is caused by the overpopulation of the bacteria named heterotrophic bacteria. It mainly occurs due to the decaying food and fish present in the tank. The decaying matters provide additional foods for the bacteria to thrive and multiply their existence in the aquarium. 

Bacterial bloom is not directly harmful to the fish, but it directly affects them. The dirty water creates more chances of exposure to new contamination and infections that are the risk in the bacterial bloom. The major reason for the bacteria to thrive is overfeeding, overpopulation of fish.

 Imbalance filtration can also support this issue, low filtration results in dirty water and over filtration kill off good bacterias present in the aquarium.

Treatment and prevention

To get rid of bacterial bloom is easy; all we need to do is follow the following steps: 

Fishless cycle

 Running the tank in the state without any fish to check for any abnormality in the tank. This will clear the deads and organics in the tanks.

Sparing feeding

 Sparing feeding the fish so there will be less of the remains in the container, which could support the growth of the heterotrophic bacteria.

Water Changes

 Water changes regularly, 25-50% every week can prevent this situation from happening. If this problem already exists, then changing water immediately after that is recommended.

 Proper filtration cleans off the dead and remaining of the foods in the water tank. Nice filtration prevents most of the problems from happening.

 If these steps are followed closely, this problem is most likely to go away. If the problem still exists even after doing all of these things better to contact the pet store and call a specialist to identify the problem.


We get excited at the beginning and tend to overfeed and over the care, and as time passed, we seem to neglect the things. There are some events in life which will make us forget about our attention to be given, but once things get normal and we notice we can fix things and bring back the old ones.

Following the basic steps mentioned above, we can keep our tank from being cloudy or recover from cloudy water.


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