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Most aquarists will, at one time or the other, experience a cloudy fish tank. This cloudiness could be a result of different reasons. Therefore as an aquarium owner, you need to identify the cause before trying to fix it.

As a common fish tank problem, the water may be milky white, yellowish, green, or even brown. Each of these colors indicates a specific problem in the aquarium. For example, the cloudy solution could be a result of algae, bacterial bloom, or tannin.

Here’s a breakdown of the most common factors that lead to cloudy fish tank water.

White or Greyish Water

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Several factors cause the water to be grayish or cloudy white.

1.  Gravel or Substrate Residue

For a new aquarium or recently changed substrate, it’s possible to encounter cloudy water. If the water forms the milky-like solution immediately after filling the fish tank, the issue could be you have improperly washed gravel. The cloudiness is caused by the dust and dirt washing off from the substrate.

To fix this, you will need to empty the tank, wash the gravel under running water until it’s properly cleaned. However, in some cases, if the gravel does not have lots of dirt, the problem might clear by itself.

2.  Dissolved Constituents

If your fish tank water remains cloudy even after cleaning the gravel, the issue could be high levels of dissolved constituents. These could be phosphates, heavy metals, or silicates. To determine whether this is the issue, you can use an aquarium water testing kit to measure the pH levels.

The alkaline water can be treated using conditioners. However, if this process does not work, you can get Reverse Osmosis water from your fish store to resolve the problem.

3.  Bacterial Bloom

In most cases, the aquarium water will take weeks or even months to turn cloudy. If this is the case with you, your tank might be dealing with bacterial bloom. This phenomenon occurs when the biological filter system is maturing.

Bacterial bloom, which is common during the initial stages of the tank cycling process can also be caused by excess food that remains uneaten or decaying plants. Over time, the beneficial bacterial colonies establish themselves and clear the waste resolving the cloudiness.

As you wait for this process to take its cause, there are several things you can do to keep the fish tank clean. For example, you can remove all uneaten food or decaying plant immediately, have regular partial water changes, vacuum the gravel and reduce the amount of food you provide your fish. Getting rid of the bacteria is essential because it affects the quality of water, which can make your fish sick.

Green Water

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A cloudy fish tank can also have green water. The leading cause of this coloration is algae growth. These plant-like organisms take over your aquarium and cover the glass, rocks inside of the glass, and grows over items on your aquarium.

Getting rid of the algae can be challenging, but you can deal with the causes that trigger the growth. Let’s look at the primary reasons.

4.  Too Much Light

Algae thrive in similar conditions to typical plants. Exposing your aquarium to direct sunlight or in a room with too much light sparks algae growth. Controlling the light exposure is the easiest way to eliminate the cloudy green water and keep the plants from coming back.

If your fish tank is near a window with direct sunlight, consider moving it away from that location. Also, limit the amount your lights are on.

5.  Nitrates

Having excess nutrients such as nitrates results in cloudy green water. Forming as a byproduct of fish waste, nitrates build up if you don’t make frequent water changes. So as soon as you change the water, carry out tests to ensure the levels are not high.

You can also keep these levels down by replacing your filter media with a nitrate-absorbing one to eliminate dissolved nitrates. Furthermore, always ensure you have not overstocked the fish to control nitrate levels.

6.  Phosphates

The decaying food matter and water source are responsible for the phosphates in your fish tank. To control this nutrient, have the water tested for excess phosphates before adding it into the tank. Otherwise, you could use RO water to be safe.

If you want to control the phosphate levels, don’t overfeed your fish; remove any excess food and dead fish, plants, and waste immediately.

Yellow or Brown Color

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The aquarium water turns into a yellowish or brown color on some occasions. Here’s the reason why.

7.  Leaching Tannins

Decorations used in the fish tank, such as driftwood, are known to leach tannins. They are added to the aquarium for fish to nibble and control the pH levels in the tank. These benefits are essential for the fish water tank, but the driftwood has some adverse effects.

Once they start leaching tannins, the water turns yellowish, making it very unattractive. This water may not harm your fish, but it’s critical to keep your aquarium water clear as much as you can.

You can prevent this occurrence by pre-soaking the driftwood in a saltwater solution until all the tannins have been drained. This process can take 3 to 7 days until the water clears up.

You can now go ahead and put the driftwood in the fish tank. Large pieces of driftwood will tend to leach tannins over time, no matter how long you soak them.

Final Thoughts

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As an aquarist, you will have an encounter with cloudy water. Getting rid of this problem in your fish tank is much easier if you understand the cause. The coloration differs most of the time and helps you narrow down the reasons why the water appears cloudy.

Having a solid maintenance routine is crucial in ensuring the aquarium stays clean, the water is changed often, and there is no decaying matter. Some of the cloudiness resolves on its own with time, but on some occasions, you have to take action immediately.

Taking precautions will save you time and money spent in fixing these issues in the future.