How to remove tannins from aquarium water

Last Updated on January 24, 2021 by cmoarz

So you just changed the water in your tank, and it’s nice and crystal clear. But later in the day, you take a look at it and what’s this! It’s as brown as tea! What the heck is up with that? Well, my friend, tannins caused this, and I’m going to teach you how to remove it from your aquarium water and bring back its awesome crystal clear quality.


There are a variety of ways to remove tannins from water such as water changes, special chemicals, or a charcoal filter.

The not so TL;DR

First, let’s talk about tannin, what is it? This is what Wikipedia has to say on the subject:

Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids.
I understand this perfectly

But you don’t need to understand any of that. All you really need to know is it makes your water brown and you want to remove it because no fish want’s to swim around in 50 gallons of tree tea. Plus it doesn’t look as nice as a crystal clear tank, after all, isn’t the point of keeping an aquarium to be able to see your beautiful fish?

Where does tannin come from?

Tannin is everywhere, in almost every species of plant. Most likely the tannin in your tank is coming from that awesome piece of driftwood you found and thought would be a great decoration.

Don’t get us wrong though, Driftwood does make incredible tank decor, and most fish love it as it’s usually got lots of nooks and crannies they can swim around and play in, or hide if need be. The problem is with untreated driftwood, and most driftwood you buy online really is going to start filling your tank up with tannin.

Should I remove them?

Whether you should is entirely a personal thing. Tannins aren’t bad for fish, in fact, Fish like it. It’s a pretty natural thing you will find in most water.

Some people like to keep that tint that tannins creates in their tank as it looks kind of nice, and really adds to the atheistic. If you’ve ever seen underwater footage of shallow water with a lot of driftwood, It’s kind of like that. Jump down to the bottom of the article to see some of the benefits of keeping tannins in your water.

But, if you do decide to go ahead and remove them, it’s pretty easily done and shouldn’t take much effort.

Removing tannins with a water change

This is the least effective method of removing tannins from your aquarium water. It takes many many 50% water changes to clear up the water and even after that, if the driftwood is still in the tank it will just get dirty again soon.

This is definitely not the recommended way to go about removing tannins. Least because of the amount of work involved for yourself but also the amount of unneeded stress put onto your fish from all the water changing.

Special tannins removal filters

This option is highly recommended over water changes and chemicals. Filters do all the work so you don’t have to, and no need to worry about potentially hurting your fish with chemicals.

Tannin filters are pretty interesting, They kind of look like water softeners, And they sort of are in a way. They are usually fairly large but you can get them in smaller more realistic sizes for your tank.

Regular carbon filters

A regular cheap carbon filter will also remove tannins really well. But the caveat here is that charcoal can remove a lot of other beneficial stuff from your aquarium.

Unfortunately, carbon fills up fast and needs to be replaced at least once a month.


My recommended chemical product is purigen. It’s not expensive and can be purchased on amazon. It acts very quickly to remove tannins from your tank.

The instructed dosing table is:

Dose in mLDose in USC
1 quart (1 L)0.25mL1/20 tsp
1 gallon (4 L)1mL1/5 tsp
5 gallons (20 L)5mL1 tsp
10 gallon (40 L)10mL2 tsp
20 gallons (80 L)20mL4 tsp
50 gallons (200 L)50mL10 tsp

Preventing tannins in the first place

It’s a very simple thing to just avoid as many tannins as possible in the first place. An option was to just not have driftwood in your tank. Obviously, that’s a bit extreme, everyone loves driftwood! So no reason to get on your knees and surrender to your new brown tea-colored overlord.

Another option is to just remove the tannins from the wood as much as possible. While wood will always leak tannins to a certain degree, You can extract a lot of it to the point where what is released isn’t noticeable. So how do you do that?

How To Remove Tannins From Driftwood

Removing tannin is very simple, Basically you just boil it away on the stove. What? that’s it?! Yup. Here are some basic instructions:

  1. Turn on the stove and boil a large pot of water, large enough for your wood.
  2. Once it’s come to a rolling boil, add your wood to the water making sure to fully submerge it.
  3. Leave it to boil for 30 minutes, Over boiling it doesn’t matter, the longer the better.
  4. Take it out and let it cool for a couple of minutes until you can handle it Then rinse it off with hot water.
  5. Give it one more thorough rinse with regular water.
  6. Finally, before adding it into a tank, let it soak in room temp water fully submerged for at least 24 hours beforehand.


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