How to Get Rid of Cloudy Water in a Fish Tank

How to Get Rid of Cloudy Water in a Fish Tank? Tips to getting Crystal Clear Aquarium Water

The question here is that, How to Get Rid of Cloudy Water in a Fish Tank?

Cloudiness of aquarium water is a common sighting for fishkeepers. This murky water condition is usually seen in newly established tanks or the tanks undergoing major water changes.

There are different types of cloudy water, and there are several reasons behind it. Thus, in this guide, we will provide you with all the information on types, causes and methods to deal with it.

Types of Cloudy Aquarium Water:

Based on the prevailing conditions in a fish tank, there can be many different colours of your aquarium water. Following are the most commonly seen cloudy water types.

  • Whitest/Grayish Water
  • Yellow/Brown Water
  • Green Water

The colour of the water indicates the underlying cause. A specific disturbance causes each condition in the aquarium ecosystem.

Whitest or Milky Water:

The cloudy water with a densely fogged appearance is the most common type of cloudy water. It is primarily seen in a new tank or the aquariums undergoing massive water changes.

Moreover, this milky sort of water is a characteristic manifestation of “NEW TANK SYNDROME”.

What is the reason behind this cloudy water condition?

So, here are several leading causes of the whitest cloudy water in the aquarium.

Dirty Gravel Used:

While adding gravel to the aquarium, there are three critical points to be kept in mind.

  1.  The gravel should be enough to cover the base of the aquarium up to 3 inches.
  2. The gravel should be of good quality as poor-quality gravel will break down in no time, adding a considerable quantity of residues to the aquarium.
  3. Always thoroughly clean the gravel and make sure it is free of any debris.

If dirty or low-quality gravel is added to the aquarium, it will turn the water milky in less than 2 hours. This is because there are not biologically beneficial Bacterias present in this substrate. Lack of bacteria can lead to excessive production of unhealthy microbes. These microbes are the main reason behind the cloudiness of water.

How to Fix this?

There is a pretty simple solution to this, first, choose a good quality substrate. This will reduce your problem to half. Next, to eradicate this issue, completely clean the substrate thoroughly before setting it in the aquarium.

If the substrate is already added, remove the water and clean the substrate and set the aquarium once again. However, this problem will rectify itself in a week with the establishment of nitrifying bacteria. But cleaning the substrate will help speed up the process.

Poor Water Quality:

In the case of clean aquarium gravel, the second most contributing factor in the cloudiness of water is poor water quality. If unfiltered tap water is used for aquarium, it is loaded with heavy metals and minerals.

Limestone is a major constituent of tap water or unfiltered water. Thus, 10% of copper, 6% calcium, 5% magnesium and up to 40ppm of nitrates are found in regular tap water. Thus, this low-quality water will result in microbial bloom leading to fogginess in the aquarium.

How to fix this issue?

Improving the water quality will significantly lower the cloudiness in water. If you are not sure about the water quality in your area, you can always test the water parameters through test kits. There are master kits available these days to test the water pH, hardness, and mineral concentration in one go.

If water quality available in your area I not suitable for aquarium, you should install Reverse osmosis Units (ROs). These units can improve water quality effectively. These filtration systems work by separating the heavy metals and minerals from water by using thin membranes.

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Unhealthy Bacterial Colonies:

One of the main reasons behind cloudiness in newly developed aquariums is the formation of microbial colonies. This bacterial bloom is mainly due to the excessive amount of minerals in the water. These bacteria can consume minerals leading to a rapid increase in microbial production.

These unhealthy bacteria are responsible for the murkiness and cloudy appearance of water.

How to solve this issue?

Well, there is not much you can do about it; give it time, and the problem will be relieved on its own. As soon as the nitrifying bacteria begin to form in the aquarium, they will effectively eliminate the bad guys.

Something you can do to multiply the effect is to reduce waste production. This can be done by vacuuming the gravel every week to eradicate any waste substances trapped in the aquarium. Set up an efficient filter in the aquarium to clean debris timely. Do not overfeed or overstock your aquarium. All these steps will decrease waste production and will remove the waste produced timely.

Massive Water Changes:

One of the greatest misconceptions about fishkeeping is that massive water changes could be beneficial. NO, water change in huge batches will eliminate any beneficial bacterial culture from the aquarium. The absence of beneficial nitrifying bacteria will result in harmful microbial bloom, thus causing cloudiness.

Major water changes can put your aquarium back to the start of the nitrogen cycle. This can cause huge disturbances in water balance.

How to perform water changes correctly?

Thus, it is recommended to perform 20-25% water change twice a month rather than 50% or more water change at once. A massive water change will eliminate useful agents, which should be avoided.

With a 25% water change after 2 weeks, a sufficient number of nitrifying bacteria are available to carry out the nitrification process. These amounts will produce more beneficial bacteria, thus saving your aquarium from harmful substances like waste, etc.

Changes in Water Filtration System:

The absence of an efficient water filtration system or mega changes in filtration can unintentionally cause a microbial bloom. Thus, effective filtration should be active all the time. Make sure to clean the filter every month in a newly established tank.

If your filter is getting clogged with waste quite frequently, it is an indicator of a heavily fed and overloaded aquarium. Thus, you should feed your fish appropriately and move some of the fish to another tank.

Yellow/Brown Aquarium Water:

Brownish murky water is only seen in certain conditions due to substantial changes brought in the tank. Still, it’s pretty unusual for a fish tank to get yellow or orange.

Following things could be responsible for giving your tank a brownish hue.

Excessive Production of Brown Algae:

Brown algae is a type of algae commonly seen in aquarium water. The production of brown algae is a sign that your aquarium is out of balance. Aquariums kept in darkness and not having visible sunlight can experience an outbreak of brown algae.

Furthermore, the presence of heavy metals like silica can also cause brown algae to bloom. This alga can give your aquarium a brownish cloudy appearance.

How to avoid over-production of brown algae?

To avoid this situation, you should first place your aquarium in a place where sunlight is available. But be cautious; too much light can lead to excessive production of green algae.

Moreover, use filtered water with a negligible concentration of heavy metals, minerals, or toxic chemicals. The water used for aquarium purposes should be free from silica. Check the water parameters regularly to algae production under check. Even a slight change in water chemistry can shift the ecosystem toward havoc.

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Abundant Concentration of Tannins:

Driftwood, Catappa leaves, or peat moss are primary sources of tannins in an aquarium. Excessive use of these tannins releasing substances can give your aquarium an orangish tinge. A small quantity of peat moss can elevate the tannins to a level that can turn your aquarium into a brown-coloured mess in no time.

This condition destroys the aquarium eco-balance; above all, it is dangerous for fish. The excessive quantity of tannins can reduce the pH to dangerously low levels. Moreover, these tannins can also destroy the aquarium aesthetics.

How to avoid tannin overload?

First of all, if you are using driftwood for decoration, use it in small concentrations. Plus, in peat moss or Catappa leaves, you can put them in the filter to ensure slow and controlled release.

This way, you can have tannins in an aquarium without changing the water color. Dried leaves on the top of the aquarium are also responsible for tannin production. So, timely wipe off any dried leaf present on the water surface.

Green Aquarium Water:

Green and cloudy aquarium water is an indication of significant algal bloom. Such cloudy water looks very unpleasing and can cause disturbances in water balance.

Let us discuss green algae in detail.

Green Algae:

Green algae or blue-green algae are frequently found in freshwater lakes and ponds. Thus, it can readily bloom in a freshwater aquarium as well. These tiny organisms can cover the decorations, plants, or substrate of the tank in no time.

This alga is particularly harmful to fish as it releases special toxins that can kill fish and mammals. Above all, dangerously high levels of this alga can deplete the tank oxygen, leading to the death of aquarium inhabitants.

How to eliminate green algae from aquarium:

Once the algae are in full bloom is almost impossible to eliminate them. But here are some beneficial methods to lower algal production.

1-Reduce the nutrients in the tank:

The algal production and growth depend on oxygen supply, light intensity, and the nutrients available. Thus, if the nutrients present in an aquarium are limited, it will limit algae production.

Leftover food particles, fish waste, and decaying organic matters constitute a significant source of nourishment for algae. Thus, restricting the nutrients can, in turn, trigger a tremendous decline in the algal bloom.

2-Decreasing the light intensity:

Just like plants, algae also need light for photosynthesis and growth. The greater the light intensity, the greater will be the extent of algae growth. The simple solution to this is to limit the exposure of aquarium to sunlight. This is quickly done by moving your aquarium to a place where there is less sunlight.

Moreover, screens are also available these days that can control the light intensity. Cutting the sunlight completely will kill your plants as well. So, controlled exposure to sunlight should be maintained in the aquarium.

3-Cut down the natural plant fertilizers:

To our surprise, there are many natural plant fertilizers present in the aquarium, which encourages algal blooming. Now you must be thinking you have not added any fertilizer.

How come there is a vast number of fertilizers in your aquarium?

The answer to this is simple that is “Nitrogen cycle”. The nitrifying bacteria can convert the waste products or leftover food particles into nitrates and nitrites.

Nitrates are essential for the growth of plants, so this nitrate act as natural plant fertilizers. Such by-products of the nitrogen cycle are responsible for excessive algae production.

Furthermore, the processed or tap water used for aquarium is loaded with phosphates, nitrates, silica, etc. These substances play a big part in green algae formation and produce a greenish hue in your aquarium.

READ  How to Reduce Nitrate levels In an Aquarium?

To eliminate these substances, regular water changes paired with thorough vacuum cleaning of substrate is vital. A 25-30% water change twice a month with weekly vacuuming of the substrate is a key to clear aquarium water.

Tips to Prevent Cloudiness of Aquarium Water:

The prominent causes of cloudiness in an aquarium have been mentioned above with their simple and effective solutions. So, now it’s time to mention some valuable tips to avoid cloudiness from ever happening.

Following are the tried and tested tips for you from some fishkeeping experts.

  1. Use carbon activated culture media:

These biological filters are responsible for eliminating elevated levels of tannins from the aquarium. Thus, it can essentially reduce the yellowish tinge from the aquarium.

  • Avoid overstocking the aquarium:

One of the main reasons behind so many aquarium related problems is overcrowding the aquarium. This leads to tremendous stress and enormously high levels of waste in the aquarium. This waste can lead to the excessive algal formation and thus cloudiness. Stock the tank according to the thumb rule, 1 gallon of water for every inch of fish.

3-Do not overfeed your fish:

Here again, overfeeding is equivalent to overstocking as it adds more waste and more leftover food in the tank. This leads to the same consequences as algal production and cloudiness in the aquarium.

The solution is simple: use the thumb rule and provide enough food to fish that they can consume in a minute or two.

     4-Establish biologically beneficial bacteria:

As mentioned before, there are some good guys in the aquarium that can fight off harmful agents, ultimately saving the fish tank from a catastrophic ending. These good guys are nitrifying bacteria. Such bacterial colonies can effectively eliminate waste from the aquarium, rendering your aquarium water crystal clear.

You can cultivate these microbes in your aquarium substrate by mixing up some substrate from a well-established aquarium. This way, your aquarium will be full of these nitrifying bacteria in no time.

Frequently Asked Questions (FAQs):

1-Will cloudy water kill my fish?

Although cloudy water can seem pretty serious condition to a beginner, there is no need to worry. Your fish can survive a spell of cloudy water. If the cloudiness is caused by algae production, there is a chance your fish can suffocate due to excessive CO2 and depletion of Oxygen. But in most cases, fish survives the cloudiness with little to no injury.

2-How long does it take for cloudy aquarium water to clear?

Cloudy water can be a nuisance for fishkeepers, but the best part is it can clear up on its own. It usually takes about 1-2 days or a maximum of a week to obtain crystal clear water on its own. All thanks to the nitrifying bacteria present in the aquarium.

3-Does cloudy water affect plants?

The cloudiness in an aquarium is caused by a bacterial and algal bloom, leading to the tank’s depletion of oxygen and nutrients. Such a tank devoid of essential nutrients cannot support plants. Thus, plant’s growth is considerably halted, and they can even die if such conditions prevail for longer durations.


The first step in treating a cloudy aquarium is to identify the type and underlying cause. The treatment is solely based on the factors that caused the condition in the first place. The good news is this condition is relatively easy to eradicate.

Furthermore, several preventive measures can ensure crystal clear water for your tank.

We hope this article will prove beneficial in coping up with cloudiness in the aquarium.

Best of luck with your aquarium!!

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