6 Factors that Lead to Cloudy Fish Tank Water

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The term aquarium is not strange to many, especially those who have fish pets at home. According to, an aquarium is a tank or vivarium where aquatic animals and plants are displayed.

If you are having an aquarium at home, then you are familiar with the problem of cloudy fish tank water or cloudy aquarium water.

An aquarium or fish tank is very significant in keeping amphibians, fish, invertebrates, and other aquatic reptiles. It is also used in keeping aquatic plants. It is water-filled, with at least two sides that are transparent.

Why is my fish tank cloudy

Why is my aquarium cloudy

The transparent sides allow one to monitor the growth and progress of the aquatic animals and plants. This, however, can only be possible if the water inside is clear. When this it turns cloudy, your aquatic life disappears in the cloud.

When it becomes cloudy, it is normal to get frustrated. In some cases, you will see cloudy water in a new fish tank. One cannot understand why this is happening. Before looking for cloudy water in fish tank solutions, it would be better to first understand the causes.

Something is wrong

According to, this phenomenon signifies a major problem. Normally, the water in an established fish tank should remain clear.  When this does not happen, then something is wrong inside it.

Understanding the factors that may cause a cloudiness is essential in managing the condition, and preventing it from happening again in future. This article, therefore, deeply examines various factors that cause it to be cloudy. It also offers rich advice on how to keep your aquarium water clear.

Key reasons why fish tank water turns cloudy

According to, this shouldn’t get you panicking. It may be an indication of a major or minor problem. One point, however, remains true; you can easily rectify the condition.

Below are some of the common reasons why fish tank water suddenly turns cloudy, even in a new one:

Accumulation of dirt and debris

If you ask many people, this is one of the main reasons why it turns cloudy. As you all know, an aquarium must contain sand and gravel. These are called substrates. They are very necessary and all of them have sand and gravel.

Prior to using them in a the tank, the substrate must be pre-washed to remove dust and debris. However, it is at times impossible to remove all of them. It can contain debris, especially the new ones.

If your substrate contains dust and debris, adding water makes everything look horrible. According to the, cloudy or murky fish tank water is mainly attributed to a dirty substrate.  This is the main reason why you hear people complain this cloudiness in a new or established tank.

This problem can, however, be managed. Make sure that your substrate is thoroughly cleaned before putting it into the aquarium. Remember it is no fish tank without the substrate. It plays an essential role in water filtration and chemistry. The health and well-being of your aquatic life also depend on your substrate.

However, a substrate can also be a source of some problems. If not properly checked, it can:

  • It makes it cloudy
  • Release harmful substances
  • Absorb essential substances from the water
  • React with other substances and affect the aquatic life.
  • Alter the chemistry of water in the aquarium
  • Alter the PH of water inside the fish tank

Therefore, caution should be taken when cleaning the substrate. Moreover, make sure that the substrate you use is chemically inert. Ensure you know how to clean aquarium gravel.

Accumulation of bacteria

According to, this is known as bacteria bloom. When the water starts turning cloudy, then it is possible that there is a bacteria bloom.

This is a common encounter, especially during aquarium cycling. For example, it getting cloudy after a change is mainly due to bacteria bloom. As we know, the fish or whatever aquatic creatures you have are continuously excreting, thus producing ammonia. There are many bacteria to consume this ammonia.

As the fish grow in size, the excretion level also goes up. Consequently, the amount of bacteria also grows. Accumulation of bacteria causes the water in the fish tank to turn milky. This shouldn’t bother you much. These bacteria are essential. Without them, your aquatic life would die due to an accumulation of ammonia.

However, this can be solved by regularly changing the water in the fish tank. You can watch this video that gives a detailed step-by-step process on how to change aquarium water.

Excessive feeding notes that giving your fish too much food can make the tank become cloudy or murky.

This happens in two ways:

  • Excess food particles making the water become cloudy
  • Excess food causing a bacterial bloom

As you feed your fish, give them what is enough. Don’t give excess. Enough means that fish will eat all of it. If you give excess, you will have a significant amount of it decaying at the bottom of your tank. This, consequently, leads to the cloudiness.

If the aquarium is already cloudy due to overfeeding, there is only one solution; changing aquarium water. You can also opt to change the substrate. Most of the decaying food particles settle at the bottom of the tank, thus contaminating the gravel.

Too many fish in one tank

On what causes milky white cloudy aquarium water, identifies that overstocking is a leading cause of cloudiness. Some people will just put too many fish in one tank.

This only means one thing; there is an excess production of ammonia due to excretion. This creates a toxic environment. The water turning cloudy only means one thing; your fish are under stress.

An aquarium, depending on the size can only accommodate a specific population of fish. This creates a stable ecosystem. When one overstocks, the ecosystem is destabilized. The water will then be turning milk or cloudy, therefore, indicates an imbalanced ecosystem.

It could be an algae bloom

This condition could also mean that water is contaminated. Pure one should be clear. A cloudy tropical fish tank may signify an overgrowth of algae. Do you know what algae are? According to, these are photosynthetic organisms that are aquatic. They appear like green slippery plants that grow at the bottom of tanks.

It is believed that excessive feeding can stimulate algae to bloom. Furthermore, those that are exposed to sunlight can also have an algae bloom.

Algae bloom is harmless. It might be a characteristic of a balanced ecosystem. However, there are times when algae may cause an imbalance in your tank. In such cases, consider changing the water in your tank. You can read more about causes and how to control aquarium algae.

Inappropriate use of filters

An aquarium is not complete without filters. These filters are known as aquarium filters. If you are having an aquarium, then a filter will be essential in removing chemical waste from your tank. This is significant in preventing it from turning cloudy. Buy good brands like MarineLand Penguin 350 BIO-Wheel Power Filter, Whisper In-Tank Filter with BioScrubber for aquariums or Aqua Clear – Fish Tank Filter.


Normally, these filters should be always turned on. This ensures that life within the tank is continuously supported. According to, the filters ensure the survival of fish within the tank. They also make the water fresh and safe for marine life.

When the filters are on, there is a continuous flow of oxygen into the fish tank. This is essential for both fish and bacteria in the aquarium. When the filters are switched off, there is a limited supply of oxygen. The bacteria start dying, thus the cloudiness.

How to get rid of cloudy fish tank water

Understanding what is ailing your fish tank is key is designing an intervention measure. Actually, one can easily manage the condition by addressing the causing factor.

You can clear cloudy aquarium water by adopting some of the following practices:

  • Reduce the amount of food you feed to your fish every day. Consider feeding them once in a day.
  • Control the population. When the population is high, it would be hard to clear cloudiness of water.
  • Change the fish tank water regularly. However, this should be done right. For example, large amount changes may alter the balance in the aquarium ecosystem.

Citations and References

  1. What causes milky white cloudy aquarium water?
  2. Cloudy Aquarium Water
  3. How to clear cloudy aquarium water
  4. Your Aquarium Has Turned Cloudy
  5. Cloudy Fish Tank Water Causes and Solutions