Rainbow shark and driftwood.

How to Remove Tannins from Aquarium Water: 5 Easy Ways

Tannins are great, but sometimes they can saturate the water column too much for fishkeepers’ tastes. They boost fish’s immune systems and help certain species reproduce. Not to mention the fact that most natural tannin sources — driftwood, leaves, cones — serve as additional food sources for shrimps and microorganisms.

Then again, too heavy tannin concentration and the water becomes darker, while the pH might drop too low. Luckily, there are several ways to remove them completely or reduce their presence to tolerable levels.

Here’s how to remove tannins from aquarium water, five easy and accessible methods:

  • Remove the tannin source
  • Frequent water changes
  • Treat the tannin source
  • Use charcoal filter
  • Use products for the purpose

Adding a reverse-osmosis filtration system will also do the trick, but that’s a rather expensive method. I’d assume that aquarists who install such systems have a fairly good idea of what they are doing.

Before we explore each tannin-removing method in detail, let’s get a better idea of what tannins are and how they impact the water of your fish tank.

What Are Tannins

Tannins are primarily composed of substances called tannic acids. They are known for their astringent properties and are commonly found in tree bark, leaves, and fruits. When these organic materials are submerged in water, tannins leach out and dissolve, leading to the discoloration of the water.

In the aquarium hobby, tannins are commonly associated with the brownish or yellowish coloration they impart to the aquarium water, often referred to as “tea-stained” or “blackwater” appearance.

Besides the visuals, they bring a slew of health benefits to the fish, lower the pH, especially if your water is soft, and mimic the natural habitat of many species.

Where Do Tannins Come From

Usually, there are three sources of tannins in aquariums:

  1. Driftwood
  2. Leaves and other botanicals
  3. Substrate

Indeed, tannins compose a large part of any organic plant matter. A driftwood will always leach tannins and so will decomposing leaves. These sources are fairly easy to detect and control.

The most subtle way tannins can discolor your water is through the substrate. If you’ve supplied yours from nature, particularly if it is rich in peat, you will have a good amount of tannins. They can visibly alter the color of your water column even if you have mostly sand or gravel. It’s enough for each of these substrates to be mixed with organic matter to produce yellowish color.

Pros and Cons of Tannins: Reasons to Keep Them or Not in Your Aquarium

Tannins are natural elements that have to be properly understood. Their impact may be desirable throughout, in certain conditions, and damaging in others.

Water discoloration is the most obvious sign of a heavy concentration of tannic acid. When its levels are high, it is likely to bind up a lot of minerals in the water column. That would lower the water hardness and alkalinity. The lower mineral count will have a negative impact on snails and other crustaceans. They need minerals to maintain their shells intact. To balance things out, you might need to add an external mineral source, like crushed coral.

Certain fish species love acidic, soft water. Discus, tetras, and loaches are big fans!

On the other hand, livebearers like guppies and mollies would suffer and are likely to exhibit signs of stress rather quickly.

In other words, tannins are good in certain contexts and not so good in others.

Use tannins sparingly if your fish prefer harder, base water. If the species you keep love brackish, acidic water, tannins are your best friend.

Can I Have Driftwood if My Fish Like Hard Water?

Driftwood will release tannins for as long as it is in the water.

But tannins lower pH and discolor the water column at high concentrations. A properly cured piece of driftwood shouldn’t change the water much, nor its chemistry. It will still be releasing tannins that will benefit the fish but at a lower, invisible rate.

In case the driftwood you bought is making the water yellowish, boil it. Boil it for a few hours if needed, and then reintroduce it to the aquarium. This usually helps. For more tips on the matter, check out this guide.

How to Remove Tannins from Aquarium Water: 5 Easy Ways

Strictly speaking, it is straightforward to remove tannins from the water column. If you want to keep the aesthetics as they are, though, things get a bit more complicated.

Still, here are the easiest ways to deal with tannins.

1. Remove the Source of Tannins

That’s fairly obvious — take out the botanicals that release tannins and there won’t be anymore. However, that often changes the way aquarium looks and does so in an undesirable fashion. Taking out a couple of leaves might be unnoticeable, but removing a couple of pieces of driftwood or half the substrate can be an eyesore.

If tannins worry you, It is best to choose species that are on the lower side of tannin saturation. Avoid Malaysian driftwood and African Moponi wood; they are better suited for brackish aquariums.

As far as substrates are concerned, choose yours carefully. Inexperienced hobbyists are better off with substrates from the fish store. Gravel is an excellent choice for beginners. Sand is another superb option for natural-looking, planted tanks.

Should you decide to remove the source, do so carefully and slowly. As with most things in the hobby, sudden changes can be dangerous for your livestock.

2. Do Regular Water Changes

Water changes help control the tannin levels. A new piece of driftwood is more likely to release tannins the first few months after submerging. Again, that depends on the tree species and how it has been cured, but over time its impact will likely diminish.

Changing the water regularly will help keep things under control.

Don’t go overboard, though. Changing 25%-40% of the water once a week for new tanks is OK. Once six months have passed, the driftwood should be leaching tannins more slowly and the balance of your tank should already make it more self-sustainable. Then you should lower the frequency and volume of water changes while keeping an eye on the water parameters.

3. Treat the Tannin Source with Boiling or Baking Soda

If the main and most constant source of tannin leaching is a piece of driftwood, you can treat it to reduce the tannic release.

Boiling the driftwood or soaking it in baking soda should lower the tannin release significantly. Baking soda binds the tannic acid quickly.

You can also keep the driftwood in a container and change its water regularly for a few weeks. This will take away the most severe leach relatively quickly without impacting the aquarium.

You can add baking soda directly to the water column, as well. Do it slowly, one dissolved teaspoon at a time (or half, if your tank is small), and test the water regularly. The soda will bind and neutralize the tannic acid, but it will also raise the pH levels. Too much baking soda can increase the pH too quickly and can send your fish into a pH shock.

4. Use a Charcoal Filtration

Charcoal filters are great for bio-filtration. They are affordable and remove all sorts of chemicals, including tannins and their stains.

Charcoal is a great anti-toxin option that will purify your water column, removing phenol and chlorine even. Keep in mind that it will neutralize rather quickly any medication you might be administering. If you have to medicate the entire tank, better remove the charcoal filter for the duration of the treatment.

Indeed, this will allow tannins to build up, but they also have many health benefits and will enhance the effect of drugs.

5. Use Purifying Products

Purigen is by far the most popular product on the market for purifying water. I’ve never used it, but the majority of reviews online are positive. I’ve seen a few complaints here and there, so I will refrain from recommending it until I have hands-on experience.

I’ve never used it because I have not needed it.

Here’s why.

Planning Makes Tannins Safe

Now that you have a working knowledge of what tannins are, you can evaluate their impact on the tank.

Tannins’ Pros:

  • Improve fish health
  • Stimulate reproduction
  • Suppress algae (in darker waters)
  • Lower pH

Tannins’ Cons (chiefly present in a high concentration of tannic acid):

  • Discolor water in high concentration
  • Can drop pH too much
  • Can reduce the concentration of minerals in the water column

Is the water discoloration truly a negative? That is up to you and the aesthetic you pursue.

The same applies to the drop in pH, as many species thrive in such environments. The softening of the water can also be desirable; if not, it can be tackled quite easily by adding minerals.

The point is that tannins are water-impacting agents. In my view, they are almost exclusively positive, but the yellowish water is not everybody’s cup of tea. (Tea and wine have plenty of tannins. That’s why they taste as good as they do but are no good for the fish.)

To avoid tannin-related issues, plan your fish tank well. Choose driftwood that has been cured, if you want crystal-clear water.

Buy the substrate.

Don’t add botanicals.

Don’t spill wine or tea inside the fish tank. 

Joking aside, it is good to know how to remove tannins from aquariums, but it is even better to not put them excessively in the water in the first place if you don’t want them. Mistakes happen and the five easy ways outlined above will help you take unwanted tannins out of your fish tank quickly, without breaking the bank.

Apply the chosen method slowly and carefully. Crystal clear water is pretty, but live and happy fish are even prettier.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *