How to Remove Tannins From Aquarium

Tannins are a natural part of the environment, but when they get into your aquarium, they can cause real problems. This is especially true in certain types of fish tanks that use live plants and other materials to create a more natural habitat. Tannins will turn the water brown or yellow and make it difficult for plants to grow, which makes for a less than ideal home for your pet fish. If you find yourself with tannin-stained water in an aquarium setup like this, don’t worry! The blog post discusses how to remove tannins from aquarium.

How to Remove Tannins From Aquarium

There are several ways to remove them. Here’s how to do it easily without spending too much money or wasting time on ineffective methods. This blog post has four paragraphs, including the intro paragraph.

Why are Tannins So Tricky to Remove?

Tannin-stained water in an aquarium occurs for several reasons. First, tannins can run into the tank through the substrate or live plants. They also leach into the water from dying leaves and other organic material that’s leftover from setting up your fish tank. The longer you let this material sit, especially if it’s not buried deep in the tank, the easier it is for tannins to get into your water.

Once they’re in there, nothing can get them out without some effort on your part. They’re not dangerous to pets at all, but they can be an eyesore and cause problems with plant growth. Therefore you want to pull them out as soon as possible before they stain the water.

There are numerous methods you can use to remove tannins from your aquarium, but most of them aren’t effective, and a few might even make the problem worse.

7 Ways on How to Remove Tannins From Aquarium

1 . Plain Water Changes

If you have a fish tank that’s already overrun with tannins, the first and easiest thing you can do is perform a water change. You’ll need to take out about twenty percent of your aquarium’s total capacity and give everything inside a good scrubbing with hot, soapy water. Then fill it right back up with clean drinking water. This will dilute the tannin-stained water and make it less visible.

Cleaning Drinking Water in Aquarium

2 . Activated Carbon

You can add activated carbon to your fish tank in order to attract any remaining tannins and pull them out of the water. This method is pretty effective, but it might absorb other essential nutrients in the process, so you have to use a lot of caution when doing it. You also have to replace the carbon once it stops working, so this method can cost you quite a bit of money over time.

3 . Alum

Adding some alum to your aquarium water will also help with tannin removal. The only problem is that many fish won’t be able to handle the high concentration of this chemical. It might even kill them if you don’t keep the dosage just right.

Adding Some Alum to Aquarium Water

4 . Activated Charcoal

Just like activated carbon, activated charcoal is a good option for removing tannins from aquarium water. You can find it in fish supply stores or pet shops and have the best luck with the pellets rather than the block form. It’s also usually much cheaper than activated carbon and still quite effective at removing sediment from your fish tank.

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5 . UV Sterilizer

UV sterilizers use ultraviolet Light to zap any living thing in your tank that’s smaller than 30 microns. This includes parasites, bacteria, algae, fungi, and viruses. If you have a lot of tannin-stained water in your fish tank, it might be hard for anything small enough to fit through the filter to live.

Uv Sterilizers Using Ultraviolet Light

6 . Reduce Light

You can make your tannin-stained water less visible by reducing the amount of Light in your fish tank. This will also help cut back on algae growth, so you might want to consider doing both at once for even better results.

7 . Keep Your Fish Healthy

Sometimes we’re so busy trying to combat a problem that we forget about the root cause. If your fish isn’t healthy and well-nourished, their immune systems won’t be able to handle any other parasites or diseases they encounter. Keep them happy and strong to help prevent future outbreaks of tannins in your water.

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Tips and Warnings


  • Always buy activated carbon or charcoal from a reputable source because some of the cheaper products have been known to release hazardous chemicals in aquarium water.
  • If you have terra cotta pots in your fish tank, check them regularly for cracks in the glaze and replace them when necessary. They can leach tannins into your water no matter how long they’ve been there.
  • If you have a lot of live plants in your aquarium, the addition of activated carbon might suck away a few essential nutrients. Don’t add it unless your fish are in serious need of relief from tannins and clumps of brown sludge!


  • Make sure to remove any activated carbon before performing your regular water change.
  • Keep an eye on activated charcoal in case it starts to discolor your aquarium water, which might indicate that it’s time to replace the filter cartridge.
  • Don’t use alum if you have fish or snails in your tank because they won’t be able to handle high concentrations of this chemical.
  • Don’t use alum to remove tannins from aquarium water if any of your fish or snails are aluminum intolerant.
  • You should avoid using UV sterilizers and activated carbon at the same time because they’ll cancel each other out.
  • Activated charcoal can slowly change the pH balance in your aquarium, so don’t use it unless you have a fairly stable pH level, to begin with.


The tips and warnings listed above are meant as general advice only. Please use your own discretion when trying any new products for the first time.

Frequently Asked Questions

Will Activated Carbon Remove Tannins?

Yes, activated carbon will remove tannins. However, it is important to note that this process may also release some toxins into the environment. Therefore, it is advisable to use a certified organic product when removing tannins with activated carbon.

What Causes Tannins in Fish Tank?

Tannins are a type of compound that is present in many plants and animals, including fish. They are responsible for the astringency found in many beverages, such as red wine. Tannins can also be found in certain fruits and vegetables, which makes them an important part of the diet for some people.

Tannins are commonly extracted from plant sources using various methods, including heat treatment or alcohol extraction. This process allows tannin-rich extract to be made into products like tea or sauce. Some people enjoy consuming these types of products because they claim that they have health benefits related to reducing inflammation or improving cholesterol levels. However, there is no evidence to support these claims at this time.

Will Tannins Harm Fish?

There is some debate on whether or not tannins in fish can be harmful. Some studies have found that high levels of tannins can actually inhibit the growth of fish, while other studies have found that tannins can actually help to repel predators. In general, it is advisable to avoid feeding your excessive fish amounts of tannins.

Do Tannins Increase PH?

Tannins are a type of fiber that can increase the acidity levels in your stomach. While this may be uncomfortable at first, over time, it may help to improve digestion and alleviate GERD symptoms.


The tannins in aquarium water can cause damage to both the fish and plants. Fortunately, there are a few simple steps that you can take to remove them from your tank. First things first, always do some research before starting any project like this one. You want to make sure that you’re doing it right so as not to have any negative effects on your aquatic life or environment. Secondly, use an algae scraper for removing those pesky brown sludge deposits left behind by dead leaves and other debris floating around in the tank. These will be loaded with tannins!

Finally, find out what kind of filter system you have going on down below and adjust accordingly based on how much time until its next cleaning cycle (usually every two weeks) and whether you intend on using activated charcoal or not. That about does it for today’s topic. Stay tuned for the next installment of aquarium knowledge brought to you by your friends at Slimeways! I hope you enjoyed this article on how to remove tannins from aquarium! Be sure to SHARE this useful information with everyone you know! Thank you for reading our article. If you have any questions or concerns, please leave a comment below!

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