How To Remove Tannins From Aquarium Water

Aquarium lovers know the fun of making a lively underwater world with lots of fish and plants. 

But sometimes, things we don’t want, like tannins, can get into our aquariums and make the water not so clear. 

In this guide, I’ll talk about tannins, what they do to your fish tank, which fish like them, what they do to the water, and most importantly, discuss methods to remove tannins from aquarium water without saying goodbye to your favorite driftwood. So let’s begin.

What Are Tannins?

Tannins are natural substances that we can find in different parts of plants, like leaves, wood, and peat. 

These tannins are what give the water in your fish tank a brownish color when you add certain things like botanicals (dried plant parts) or driftwood.

Tannins as tiny particles or molecules in these plant materials that can make the water look brownish. 

It’s like when you make tea – the tea leaves release tannins into the water, giving it a brownish or amber color. 

In your aquarium, the plant materials release tannins, which can change the color of the water. Some people like this natural look in their aquariums, while others prefer clear water, so it depends on your personal preference.

How Does Tannin Come To A Fish Tank?

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1. Natural Sources

Tannins usually find their way into an aquarium in a very natural way. It happens when you put things like leaves or pieces of wood into the tank. 

These materials have tannins stored inside them. Over time, as they get wet and soak in the aquarium water, they start to break down. 

When they break down, they release those tannins into the water. It’s a bit like how sugar dissolves in your tea when you stir it.

2. Intentional Addition

Some people who take care of fish tanks do something special. They deliberately put leaves, wood, or other things that they know contain tannins into their tank. 

They do this because tannins can change the water’s color and create an environment that looks more like where the fish come from in nature. 

Fish from places like the Amazon River, for example, live in water that often has a brownish tint because of tannins from the leaves and wood in the water.

So, tannins can enter a fish tank either naturally through things like leaves and wood, or by choice, when aquarium enthusiasts want to give their fish a home that feels closer to their natural habitat.

What Is The Impact Of Tannins In Aquariums?

Positive Impacts of Tannins:

1. Natural-looking Water

Tannins can make your aquarium water look like the kind of water fish find in their natural homes. For some people, this natural, slightly brownish color is really appealing because it mimics the fish’s environment in the wild.

2. Fish Health

In certain cases, tannins can create water conditions that are good for your fish. For example, some fish species, like much Amazonian fish, prefer slightly acidic and soft water, which is what tannins can help create. So, for these fish, tannins can actually be beneficial.

3. Reduces Stress

Some fish might feel less stressed in water with tannins because it resemble their natural habitat. This can be especially helpful when you’re introducing new fish to your tank or if you have sensitive species.

Negative Impacts of Tannins:

1. Water Clarity

Tannins can make your aquarium water look a bit murky or brownish. If you prefer crystal-clear water, this might not be what you want.

2. pH Levels

Tannins can make the water slightly acidic. While this is good for some fish, it might not be ideal for others. It all depends on the specific fish you have in your tank and their preferences for water conditions.

In summary, tannins in your aquarium can make the water look more natural and benefit certain fish species. 

However, they can also affect water clarity and pH levels, which might not be suitable for all fish. 

So, whether tannins are a good or bad thing for your aquarium depends on the types of fish you keep and your personal taste in aquarium aesthetics.

Which Types Of Fish Require Tannins?

1. Amazonian Tetras

These are small, colorful fish found in the Amazon River. They’re used to living in water that has a bit of a brownish tint because of tannins from leaves and wood. So, they feel most at home in aquariums with tannin-rich water.

2. Angelfish

These elegant, flat-bodied fish also come from the Amazon River area. Like Amazonian tetras, they prefer water with tannins because it’s what they’re used to in the wild.

3. Discus

Discus fish are known for their round, flat bodies and vibrant colors. 

They are very particular about their water conditions, and they come from areas where there are lots of tannins in the water. So, they do best in aquariums with tannin-rich water.

For these fish, tannins help recreate the conditions they’re used to in their natural homes. It makes them feel comfortable and more at ease in your aquarium, which can be really good for their health and well-being. 

So, if you have these fish, adding tannins to their tank is like giving them a taste of home.

What Are The Effects Of Tannins In Water?

1. Water Coloring

Tannins are like tiny natural color-makers. When they get into the water, they can turn it a bit brown, kind of like how tea looks. 

This happens because tannins dissolve in water, and as they do, they give it a brownish or tea-like color.

Now, some people who take care of aquariums really like this look. They find it beautiful and natural. 

It’s like having a piece of a wild river or lake in their home. It can even make the colors of the fish and plants in the tank pop out more because of the contrast with the brownish water.

But not everyone likes it. Some folks prefer their aquarium water to be super clear, like glass. They think it looks cleaner and shows off their fish more clearly. 

So, whether the water looks like tea or stays crystal clear depends on what you and your fish prefer in terms of appearance. It’s all about your personal taste.

2. Lower pH

pH is like a measurement that tells us how acidic or basic water is. It’s a scale from 0 to 14, where 7 is neutral (neither acidic nor basic), lower numbers are acidic, and higher numbers are basic.

Tannins have a special power: they can make the water a bit more acidic, which means it moves toward the lower numbers on the pH scale. Think of it like adding a squeeze of lemon juice to water, making it slightly sour.

Now, this can be really helpful for some fish. Some fish, like those from the Amazon River, where there are lots of tannins, prefer their water to be a bit on the acidic side. It’s like having the right seasoning for their environment.

But not all fish like acidic water. Some prefer it more neutral or even slightly basic. So, whether tannins are good or not depends on the specific kind of fish you have in your tank. For those who like it a bit sour, tannins can make them feel right at home.

3. Antioxidant Properties

Tannins  have a special power called “antioxidant properties.” These properties work a bit like a shield that protects your fish from harm.

One of the amazing things antioxidants do is reduce stress in fish. Just like how a cozy blanket can make you feel relaxed, tannins can make fish feel less stressed in their tank. When fish are less stressed, they’re happier and healthier.

But that’s not all. These tannins also promote overall well-being. They help keep your fish in good shape, by eating nutritious food and exercising. So, having tannins in the water can be like giving your fish a healthy lifestyle.

Possible Benefits Of Tannins In Your Aquarium

1. Stress Reduction

Tannins work like a natural relaxer for your fish. They make the water in your tank feel like a cozy and peaceful hideaway. 

Just as a cozy room helps you feel more relaxed, tannins do the same for your fish. When fish are less stressed, they tend to be calmer and less likely to get into fights with each other. So, tannins create a calm and friendly atmosphere in your aquarium.

2. Health Benefits

Now, tannins have another special power – they act like protective shields for your fish. These shields are called antioxidants. 

They work a bit like vitamins for your fish. When your fish have enough antioxidants from tannins, it’s like giving them a strong immune system. 

They become less likely to get sick, just like eating healthy foods helps you stay well. So, tannins can make your fish healthier and more resistant to diseases, which is great for their overall well-being.

Methods to Remove Tannins From Aquarium Water

If you’ve decided that the tannins in your aquarium are causing more harm than good or if you simply prefer clear water, here are some methods to remove them:

What Is The Best Way To Remove Tannins From A Tank Without Removing The Driftwood?

1. Activated Carbon

In your aquarium, you have a filter that helps keep the water clean. You can make this filter your tannin-removal helper. Inside the filter, there’s something called “activated carbon.” This special carbon is like a sponge for tannins – it soaks them up from the water.

Here’s how it works: The water in your tank flows through the filter, and as it does, the activated carbon in there traps the tannins, just like how a sponge soaks up spilled juice.

But remember, this activated carbon doesn’t last forever. Over time, it gets full of tannins and stops working. 

So, you need to replace it regularly to keep it effective. It’s like changing a full sponge for a fresh one when you’re cleaning up a mess. 

This way, you can keep your water clear and tannin-free while still enjoying the look of your driftwood in the tank.

2. Partial Water Changes

Think of your aquarium as a big container of juice, and tannins are like a strong fruit flavour in that juice. 

To make it less intense, you can pour out some of the juice and add fresh juice.

In your fish tank, this means taking out some of the water and putting in new, clean water.

When you do this regularly, it helps make the tannins in the tank weaker, so the water doesn’t look as brown.

But here’s the thing: If you have lots of driftwood in your tank that’s releasing a ton of tannins, this method might not completely remove them. 

It’s a bit like trying to make very strong juice less strong by adding a bit of water – it can help, but if the juice is super strong, you might still taste the flavour. 

So, if your tank has lots of driftwood, you might need to use other methods, like activated carbon, to completely get rid of the tannins.

3. Chemical Resins

There are some special things made just for aquariums called “resins.” These resins are like little helpers that are really good at grabbing tannins and taking them out of the water.

Here’s how you can use them: You can put these resins inside your aquarium filter, kind of like putting tea leaves in a tea bag. 

When the water flows through the filter, these resins catch the tannins, just like how a tea bag holds the tea flavour.

Another way is to place these resins in a small bag and put the bag in your aquarium. The water passes through the bag, and the resins inside it work to remove the tannins.

So, these resins are like special clean-up crews for tannins in your aquarium. They help keep your water clear and free from that brownish color that tannins can create.

4. Boiling Driftwood

If the wood in your aquarium is the main reason your water has tannins and it’s not too big, you can give it a hot bath before putting it in the tank. 

Boiling helps the wood release tannins into the water before you add it to your aquarium.

Here’s how it works: You take the driftwood, put it in a big pot, and cover it with water. Then, you heat up the water until it’s boiling, just like when you make pasta. 

This boiling process makes the tannins in the wood come out and mix with the water in the pot.

Once you’ve boiled it for a while and the water has turned brownish, you can take the driftwood out and let it cool. 

After it’s cooled down, you can safely put it in your aquarium. Since a lot of the tannins have already come out during boiling, it won’t have as much of an impact on the water in your tank.

So, by boiling the driftwood first, you’re kind of giving it a tannin bath before it meets your fish, which can help keep your aquarium water from turning too brown.

5, Poly filter pads

These pads are specially made to grab onto the stuff that makes your water brown. When they catch these yucky things, they change color, showing you that they’re working.

Using them is a breeze. Just put a Polyfilter pad in your filter or a place with strong water flow in your tank. It will do its job there.

These pads are pretty good at their job. They’re easy to use and can help keep your water looking clean and clear by getting rid of tannins and other junk.

So, if you want a simple way to keep your aquarium water looking great, consider using Polyfilter pads. They’re like your water’s personal cleanup crew!


To sum it up, tannins can bring both good and not-so-good things to your aquarium hobby. It’s important to know how they work and how to deal with them to keep your fish happy and your tank looking great.

You can decide if you want your water to have that natural tannin look or if you prefer it to be super clear – it’s your choice. 

By using the methods we talked about, you can make sure your fish are living in the conditions they like best while still having a beautiful underwater world to enjoy.


How long does it take for tannins to go away?

Tannins can take a while to disappear from your aquarium. It depends on things like how much driftwood you have and how often you do water changes. Sometimes it can be a few weeks, and sometimes it might take a few months.

Does carbon remove tannins from aquariums?

Yes, activated carbon in your filter can help remove tannins from the water. It acts like a sponge to soak them up. But remember, you need to change the carbon regularly to keep it working.

How do you remove tannins naturally?

To remove tannins naturally, you can do regular water changes. This dilutes the tannins by taking out some water and adding fresh, clean water.

Also, using certain types of plants or chemicals can help, but it’s best to start with water changes.

Are tannins harmful to fish?

Tannins are usually not harmful to fish. In fact, some fish, like those from the Amazon River, like tannins because they make the water more like their natural home. But too many tannins can make the water too dark, which might stress some fish.

Do tannins help sick fish?

Tannins can sometimes help sick fish because they create a soothing environment. But they’re not a cure for all fish illnesses.

It’s important to figure out what’s wrong with your fish and use the right treatments if they’re sick. Tannins are more like a comfort thing for fish.

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