Why Is My Aquarium Water Cloudy? This Is Why.

Last Updated on January 24, 2021 by cmoarz

Keeping an aquarium is more than just a fun activity; it is also rewarding. But did you know most people don’t know how to clean their tanks properly? They end up asking questions like “Why Is My Aquarium Water Cloudy” while slowly pulling out their own hair?

It is crucial to ensure you maintain a high cleanliness level in your aquarium, and that also means doing it properly. Your fishy friends depend on it!


Cleaning the fish tank is essential; failure will lead to the aquarium being saturated with ammonia, nitrates, and nitrites. The chemicals can have dire consequences for aquatic life. As a result, the fish might lose appetite, have less coordination, have less energy, and even a weak immune system. Eventually, it might cause death.

In the ocean, or a river or lake, Mother nature acts as the fish tank cleaner. And you know what? She does a great job at it. But unfortunately, you don’t have access to her in your home, so it’s all on you to take appropriate action to keep your environment healthy, clean, clear, and HAPPY.


Various reasons affect the duration you will take to clean out your tank. One critical determinant is the number of fishes you have. The more populated your fish tank is, the higher the rate of harmful chemical production. Thus, for highly populated aquariums, cleaning should be at least twice a month and for the sparsely populated tank once.

However, ensure you test the water regularly to warrant it does not have a high content of harmful chemicals. In case you notice the dangerous chemicals content levels are high, the best option is to clean it. Cleaning will not only keep the aquatic life safe, but it will also increase the curb appeal of the tank.

It is essential to be cautious with the chemical you use in cleaning the system. Avoid harsh chemicals as they might be dangerous for the fish.


After cleaning out the aquarium, you do not only expect it to be clean; you also expect the water to be clear. Issues like cloudy aquarium water can be frustrating and will also compromise the appeal. If you have such problems, it is best to understand the causes and solutions to these issues.


You might be wondering why my fish tank is cloudy after cleaning or after a water change. One mistake people make after cleaning their fish tank is to forget washing the gravel. Before returning the sand to the fish tank, ensure you have properly cleaned it. If you fail, the water will turn cloudy within the first few hours after putting it in the fish tank.

The substrates will create fine specks when they rub together. The specs are not easily noticeable since they are small. When you add the gravel without washing, it will turn the water cloudy. The color will be whitish, almost milk-like. The issue can be avoided if you clean your sand.


The good news is that cleaning out the residue from the gravel is easy, and you can easily do it yourself. You can change the water to get rid of any floating elements you might not need. In case the fish tank has a mechanical filtration system, you can wait. After some time, the system will trap the dust. Therefore, you will see the cloudy water clearing out. Ensure you have installed the best gravel vacuum for your tank.


Bacteria in your aquarium will cause a white-like cloud. If you notice such a color, it is a warning sign of bacterial swimming in the tank. The cloudiness in the tank is caused by millions of bacteria swimming in the water.

Though you can’t see bacteria when the number grows, you will end up with a tank that looks unclear. That is known as the bacterial haze, and depending on how advanced it is, the tank’s color can range from fog to deep white. The bacteria are caused by rotting fish food, poop build-up, and plants decaying.


If you are using a fish tank with an automated cleaning system, this will not stress you. The system will clean out the bacterial, and within a few days, you will enjoy a clean looking tank.

However, if the tank does not have a cleaning system, you are the one who will need to manage the issue manually. Test the water to get the chemical level. If it has high levels of dangerous chemicals, you will have to change the water.

If the levels are normal, it might be that you have killed off the good bacteria. Thus, you might need to cycle the tank water with the fish still inside the tank.


Driftwood is known to make the water in the fish tank yellow. If you do not manage the situation, it might darken to almost dark brown. Such a fish tank is not only unhealthy for your fish; it is also unappealing.

Seed pods, leaves, and wood are known to release a dark brown dye when left in water. The product is known as tannin. As the tannin being produced grows, it will turn your water into a yellow-brown shade.


For a more in depth solution check out our article on removing tannin’s

The amount of tannin that will be released in the water will depend on the type of driftwood. Some are known to offer a light shade, while others will have a dark brown color.

If you want to have the wood in your aquarium but are not a fan of the yellow-brown color, you can start by pre-soaking the driftwood before you place it in your fish tank. You can boil water to speed up the process.

In case you had used the wood without pre-soaking it, then it might have turned your tank and the products in it brown. If so, you can use a carbon filter to help you remove any unwanted colors in your tank and leave you with clear waters.


After dealing with the substrate, bacteria, and driftwood and wondering why my fish tank is still cloudy, it might be the phytoplankton. Though they are not visible with the naked eye, when they grow in the number, they are noticeable as they will turn the transparent water green. Before you get overworked with these algae, note that it will not harm the fish.


What you should note is that the A UV sterilizer will help in dealing with the cloudy mess. However, to ensure you do not deal with algae issues again, get to the root of the matter. Failing to change the water, imbalance fertilizers, too many light and dirty filters are some issues that might cause the green mess.


The highlighted are some top causes of a cloudy aquarium. They come in different colors, and you can manage the issue depending on what has caused the discoloration. After dealing with the issue, you will have a clear fish tank for you to enjoy. So if you ever hear a friend or someone else ask “Why Is My Aquarium Water Cloudy?”, Send them to this article!


Owner of AquariumGravel.com and also owner of actual Aquarium Gravel believe it or not! ;). Setting up beautiful aquarium sceneries and habitats since I was very young. Enjoy!