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How to Clean a Cloudy Aquarium?

by Mr.Knowledgeable 21 May 2024 Комментариев: 0

Fishkeeping is a popular hobby, and a healthy, well-planted aquarium filled with beautiful fish can transform any space. Enjoying nature in the comfort of your own home through an aquarium has many benefits. However, many aquarium owners find it challenging to maintain optimal water quality in their aquariums, especially in newly set-up tanks. In this article, we'll explore what causes aquarium water to become cloudy and what we can do to permanently fix cloudy water.

Aquarium Water

An aquarium is a micro-ecosystem and a home to many different organisms coexisting. Finding a balance is key to having a happy and healthy aquarium with many inhabitants. For example, among the livestock in your aquarium, there are millions of bacteria—some good, some bad.

Your aquarium residents, such as shrimp, fish, and snails, must breathe oxygen dissolved in the water column. In doing so, they also unfortunately contribute to the necessity of water quality. Cloudy water clearly indicates issues with your water quality. Not to mention the unpleasant odor.

What Causes Your Aquarium to Become Cloudy?

As fish keepers, we cannot forget that we are also fish keepers. The importance of maintaining a healthy colony of nitrifying bacteria cannot be overstated. A healthy colony will help combat algae and protozoa by consuming unwanted nitrates and other waste products produced in the aquarium. When there are not enough good bacteria present, waste produced by the fish cannot be effectively broken down, leading to a proliferation of bacteria. We see this happen in the form of cloudy water.

Immature Tanks

Cloudiness in a newly set-up aquarium may indicate that the aquarium has not yet established optimal living conditions for the fish. In other words, the nitrogen cycle has not been completed. If that's the case, patience is a virtue. Wait a few days, and beneficial bacteria will arrive. Avoid any drastic water changes that would slow down the process. Good bacteria ensure a balanced ecosystem. Cycling a tank naturally takes about four weeks. Cloudy water in a new aquarium is most commonly caused by an excess of waste and a lack of bacteria. In our blog, you can learn about ammonia, nitrite, beneficial bacteria, and aquarium ecosystems!

Enthusiastic Water Changes

Cloudy water can also occur after water changes. Performing this operation too frequently and sterilizing filter media can disrupt the balance and harm the development of beneficial bacteria. This hinders the aquarium's natural ability to process waste elements. This situation provides an ideal environment for protozoa.

Inadequate Decorations

Especially unprepared or overly fresh wood. Additionally, synthetic decorations with debris buildup on them can cause the water to become cloudy. Read more about choosing the right decorations for your aquarium in our recent blog!

Improper Substrate

Using the wrong substrate can lead to the rotting process. Then the water in the tank becomes darker, like tea.


Feeding animals too frequently or too much. Uneaten food should be treated as fish waste. Excess waste in the fish tank only means one thing—poor water quality. Therefore, we strongly recommend reducing the frequency and quantity of feeding.

Excess Food and Fish Waste

Pollution in the aquarium can lead to cloudy water. Additionally, neglected substrates with debris buildup directly lead to cloudy water production.

Other Reasons

Other reasons include:

  • Poor water change procedures.

  • Inadequate filtration. Insufficient flow or ineffective filter media.

Addressing Cloudy Water in the Aquarium

Addressing cloudy water in the aquarium is possible through some simple changes. Adding fish to a new aquarium. Adding fish can help develop existing bacteria colonies and increase their efficiency in processing the bacteria causing cloudy water. As mentioned earlier, wait four weeks before adding any livestock to naturally cycle your aquarium.定期换水对于保持水族箱的健康至关重要

Water Changes

Established aquariums should have 20% to 40% of their water changed weekly or every two weeks.

Aquarium Filter

Your aquarium filter should be chosen according to the size of the aquarium. When cleaning the filter itself, only use aquarium water to clean the filter media. Anything else will destroy the important bacteria living within its porous surfaces. To be an effective filter, it should run 24/7 and never be turned off. To support filtration, consider introducing some species from the cleaning crew. Otos, Amano shrimp, or Black Molly are excellent choices for this job. Additionally, they will help you combat algae growth and have clear water.经典的虹吸式砾石清洁剂非常适合保持清洁和健康的基质。

Substrate Cleaning

Remember to remove the bottom gravel or coarse sand during water changes. Be cautious with plant soil substrates. Replace fine sand with large-grain sand of 2-4mm. This will provide an ideal surface for more beneficial bacteria colonization. The depth of the substrate should not exceed about 5-7 centimeters.


Feeding too much can lead to cloudy water in the fish tank. An adult fish only needs to be fed once or twice a day. Always ensure that the food is eaten within a few minutes. Afterwards, remove any leftover food to prevent unnecessary issues.

Maintain Healthy Live Plants and Clean Hardscapes.

Inspect hard landscaping materials such as wood and stone for any signs of decay. This also applies to live plants. If the leaves are allowed to rot, they can develop into problems. Check if there is any dirt buildup on rocks or stones. If left for too long, chemical properties of the water try will be affected.

Green Water in the Aquarium

The water in the tank can also turn brown or green. Cloudy substrate can cause brownish water. To address this issue, carefully remove the top layer of substrate during water changes. Using filter floss in your filter can be helpful.While single-celled algae can produce green water, cloudy aquarium water may also be caused by the following:

  • Incorrect lighting. Too strong for too long!

  • Lack of adequate filtration.

  • Direct sunlight all day.

  • Insufficient bottom detoxification.

  • Insufficient water changes

Algae and protozoa may coexist in immature aquariums lacking nitrifying bacteria. Aeration is essential as algae absorb a lot of oxygen. Put fewer livestock.

To address green water in the aquarium, it's worth shutting off the lights or reducing the lighting duration. Typically, this should suffice for about three days. After this period, the issue should dissipate. You should also remove the aquarium from direct sunlight and perform a water change to facilitate effective biological filtration. Using filter cartridges designed to eliminate algae growth can also be used in the filter.

In cases of particularly heavy bloom, special preparations may be needed to address green cloudy water, including a particularly powerful skimmer. However, in the absence of one, you can employ copious amounts of activated carbon and vigorous water circulation. Lowering the water temperature to 79 degrees Fahrenheit is also a good idea.

Cloudy water is caused by mechanical factors. When tiny undissolved particles in the aquarium water are too small to be retained on filter sponges, this occurs. Conversely, the continuous movement of water makes it cloudy. Typically, this problem occurs in new fish tanks, such as when new gravel has not been rinsed well.

In such cases, you can replace all of the aquarium water, which requires a considerable amount of time. Therefore, it's best to insert specific filter cartridges made of dense wool into the filter. It will capture floating particles. You can also partially replace the water until it becomes clear.

How to Avoid Cloudy Water in the Fish Tank?

Do not introduce fish into the aquarium until a significant amount of beneficial bacteria has been established. This can cause problems, even leading to the death of new fish, before the aquarium has had time to establish a sufficient population of aerobic bacteria, resulting in a decrease in oxygen levels as the water becomes stagnant, depriving fish of the opportunity to breathe freely.

Aquarium water testing will inform you of what you're dealing with and when to introduce fish. After checking water parameters such as NH4 and NO2, you can see when the filter is being touched and when you can start adding fish.

To find out if there are too many fish in your fish tank, check for NO3. As long as the test shows nitrogen compounds, you can have as many fish as possible.

In most cases, aquarium water becomes cloudy due to natural causes, so it's best to clear it using natural methods. Regular water changes and monitoring water parameters to keep fish happy and healthy are also worthwhile. They will surely provide you with exquisite decorations, such as a well-maintained aquarium.

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