Causes and Fixes for Yellow or Brown Aquarium Water

Causes and Fixes for Yellow or Brown Aquarium Water

Why is the aquarium water brown or yellow, and how to fix this problem? In this article, learn everything you need to do to make your water crystal clear!

       Typically, aquarium water should be crystal clear. But if your aquarium water is brown or yellowish, there could be something wrong with the system.

       You might be wondering why the aquarium water is brown or yellow, right? Most of the time, an aquarium with water this color is a cause for concern. This could mean that the aquarium’s health is at risk.

       However, changes in the color of the water do not always interfere with the health and well-being of the fish so we will address them all in this article!

       By the way, today you will learn a little about the reasons that can cause this problem and methods on how to solve it quickly and easily. Remember that your fish must be swimming in crystal clear and healthy waters!

What are the main reasons that turn the water brown or yellow?

Overgrown of algae or other microorganisms

       When your aquarium turns yellow or brown, it can signifies an algae bloom.

       Algae are microorganisms that can contaminate water and cause it to turn yellow or brown. Also, they are usually green, but when they settle in aquarium water, they turn yellow.

Your aquarium contains a high concentration of tannins

       Sometimes brown or yellow water is not something you should be worried about. Some decorations, such as driftwood or leaves, can release a substance into the water known as tannin. Tannin is not harmful to the aquarium in general. Tannin is a natural substance that wood or leaves drop into the water, which helps to lower the pH.

       In nature, tannin often colors the water of rivers and lakes, leaving them these yellow and brown colors. The same thing happens in your aquarium when you add some plant matter. By looking at it, you’ll know the brown watercolor is due to tannin. If it doesn’t look cloudy, that’s a good indication that tannins are to blame, so there’s not much to worry about.

       Some fish species prefer darker waters and thrive in these conditions. Make sure your fish do well in softer water with a lower pH.

Decomposing organic matter

       Cloudy, yellowish water is a sign that your aquatic environment is polluted. Organic materials such as food, fish waste, plants, and other rotten substances can create an unbearable environment for animals.

       The foul smell usually accompanies the yellow color of the aquarium water if the reason was not the tannins. This means that the aquarium is full of decaying material or has a biological load that the filter cannot handle. Trust me; you will want to remedy these issues as soon as possible. Fish cannot survive for long in this type of environment. They will get sick and die!

       Again, this staining can be caused by any number of reasons. Perhaps your fish produce too much waste and create a very high bio-load in the aquarium. Remember that fish pee and poop just like any other animal. So, if you don’t have a decent filter or don’t perform regular maintenance, the water will change color!

       If you have a planted aquarium, the leaves that fall from the plants and stay on the bottom can cause this brown or yellow color. So try to get rid of them!

You didn’t wash the substrate properly.

       New aquariums are the most likely to have problems with water quality. As soon as you set up the aquarium, the water starts to turn yellow or cloudy. This is because the substrate was not washed properly. The substrate contains dust and other types of contaminants.

       If you just put it in the aquarium, the water might turn a different color. So, before putting it on, try washing it. Therefore, some substrates contain tannins, which can cause the paint to brown or yellow.

How to fix brown/yellow aquarium water?

Check the water conditions

       Before making any changes to the aquarium, test the water in the aquarium. This is the easiest way to find out what’s wrong. First, check your nitrite, nitrate, ammonia, and pH levels. These measurements will tell you if you have a problem with debris inside your aquarium. And if that’s the case, you’ll likely have to fix the chemistry with a partial water change.

       Also, look and see if there is a lot of debris on the bottom or floating around. Plant matter floating in the water can also cause this problem. If you have dead plants, decaying feed, or other particles, they can turn your water yellow or brown.

       If the aquarium is very large, check that there are no dead fish hidden in any decor. This can cause even more severe problems!

Check your filtering system

       A good aquarium filter makes all the difference. Waste and other contaminants build up when you don’t have a proper filter.

Keep in mind that your filter needs to have a power of 5 to 10 times the volume of the aquarium.

       Want an example? Suppose you have an aquarium with 10 gallons. In that case, your filter will have to pass at least 50 gallons per hour through it, but this will logically depend on the species you keep and the amount of biological load they generate within the environment.

       So if your aquarium filter is not working correctly, the chance that you will have problems with yellow or brown water will be very high. If you start to notice that the water is turning this color, look at the filter. Thoroughly clean the biological media (using aquarium water) and everything else inside.

       Treat the driftwood before placing them in the aquarium and wash the substrate.

       If tannins are causing your aquarium water to turn brown or yellowish, you don’t have to worry about “fixing” it right away. However, not everyone likes to have an aquarium with darker waters. You can take the wood out of the aquarium and treat it.

       As we said before, before adding any substrate to the aquarium, wash it thoroughly! Some of them can come with tannins and a lot of dust, causing problems with the quality of the water and leaving it cloudy or yellowish.

Perform a partial water change

       A partial water change will make your aquarium water crystal clear again, even if fish residues are the main reason for leaving the water with this color. But you will need to analyze what factors are causing this problem so that it does not occur in the future.

Get rid of decaying materials

       In addition to performing partial water changes, you will need to remove any debris in the water. If you don’t remove the decaying organic matter, your new water will quickly turn yellow.

       Get rid of everything that is rotting or that could deteriorate. This includes dead plants and animals, as well as food scraps.

Create a maintenance routine

       It would be best if you created a maintenance routine for your aquarium. It’s no use leaving it in the corner for several days! You need to keep an eye on it and perform partial water changes frequently.

       Many types of equipment help in maintaining an aquarium. A siphon is an item that you can invest in, as it helps to remove waste that accumulates in the substrate. Also, they are very useful when you are performing partial water changes.

       Water changes need to be done every week or two. However, this will depend on the size of your aquarium and the amount of biological load it carries.

Use products to make the water crystal clear

       Some great products can help get your aquarium water crystal clear again.


       Doing all that we talked about in this article, it is improbable that your aquarium will have brown or yellow water again! Remember that if you consistently pay attention to the general appearance of the aquarium, your water will hardly change color! Believe it!

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