yellow aquarium water

It can be concerning if your aquarium water suddenly turns yellow. Not only doesn’t it ruin your tank’s aesthetic, but it might also be harmful for your pets. In today’s article, I will explain why your aquarium water is turning yellow and discuss how to fix it.

Why is my aquarium water yellow?

The main reasons your aquarium water is yellow is because of driftwood/plants, dirty filter, and algae buildup.

How to clear up yellow aquarium water

Most of the time, you can clear up your yellow aquarium water by performing water changes, cleaning your filter, and cleaning items before you put them in your tank.

However, the steps you’ll need to take will depend on what is causing the yellow tint in your aquarium water.


aquarium water yellow tint

The main reason your aquarium water looks yellow is because of driftwood or plants that you put in the tank. Driftwood usually has a substance called tannins that seeps into the water and creates a yellowish color.

Tannins can also leak from certain plants that you put in your aquarium. Sometimes the aquarium water will still look clear but with a yellow tint. Luckily tannins are not dangerous for fish or turtles, but they do ruin the aesthetic of your aquarium. Especially if you have fancy driftwood such as a bonsai tree.

To help prevent this from happening in the future, you should boil any driftwood before you put it in your aquarium. This will help remove the tannins before they enter your tank. You can learn more in my article on how to prepare driftwood for an aquarium.

If your water is yellow from driftwood, your filter might be able to clear things up in a couple days. However, you might need to do a 75% water change if the problem doesn’t resolve in a week or two.

If the water continues to stay yellow, you might just need to choose a different piece of driftwood. You can learn more in my video below.

Dirty filter

Another reason that your aquarium water is yellow is because you are not cleaning your filter frequently enough. Depending on the type of filter, you might need to clean your filter every other week. Other filters might only require it once a month or so.

Many people don’t realize that a dirty filter is unable to clean water, and essentially becomes useless until you give it a clean.

If you want to help optimize your filter’s performance, I suggest you use this cleaning solution.

solution for yellow aquarium water

It is also important to regularly replace the filter media. You should check the instruction manual on your filter to see how often they recommend you change the media.

If this still doesn’t work, you might just need to get a new filter. I highly recommend this AQUA-ATL filter. It cycles 480 gallons per hour, and costs less than $40.

Along with a yellow tint, a dirty filter might also make your aquarium water cloudy. In this case, you might need to do a full water change. Below is a video on how to do this.

Algae buildup

aquarium water turning yellow

While most algae is green, it can turn into a cloudy, yellowish color after being in water for a long period of time. Algae can be a real pain, so it is important to stop its growth as soon as possible.

You should start by removing any large pieces of algae that you can easily scoop up with your net or hand. Next you should put in an algae control solution which will help stop the growth of algae in the future. There are a couple cheap options that you can buy on amazon.

To help prevent the growth of algae, you should make sure that you don’t have your aquarium or basking lights on for more than 12 hours a day, as algae synthesizes light for food. If your fish tank is next to a window that receives a lot of light, you might want to consider moving your tank to a darker room.

It might take a couple days for your water to clear up after you remove the algae. You can help speed up the process by performing a water change.

You might also want to consider getting cleaning fish for your tank, which eat algae as their food.


There is also a chance that your substrate is the reason your aquarium water is yellow. The yellow tint can be a result of the dust or dirt on your substrate. Therefore, it is important to always clean substrate before you put it in your aquarium.

Tips for preventing yellow aquarium water

To help prevent yellow aquarium water, you should perform regular water changes. This will help dilute the yellow tint in your water.

You should also make sure to regularly clean your aquarium. Make sure to do some spot cleaning and remove any debris/buildup when you see it. It’s also very important to remove any uneaten food from your aquarium, as food will eventually decompose and make your water dirty.

Lastly, make sure you have a filter that is strong enough for your tank. A lot of times people will get a filter that doesn’t filter enough of the water in the aquarium. Not only can this lead to yellow water, but it can also cause harm to your fish.