How To Use Charcoal In A Pond Filter

Activated charcoal powder on table for beauty treatment

Activated charcoal can offer many benefits to pond owners, but it is a relatively new product in pond cleanliness. Activated charcoal has increased in popularity over the years due to the benefits it can offer your pond, but how do you use activated charcoal in a pond filter?

Activated charcoal can only be used in newer model pond filters as they have a section that is generally at the bottom of the filter that can be screwed off, and activated charcoal can be placed inside. If you don’t have a newer filter, you can still use charcoal by placing it in a mesh filter bag. 

What does activated charcoal remove from pond water? How does activated charcoal work? What are the benefits of using activated charcoal in your pond? Let’s find out!

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How To Use Charcoal In Your Pond Filter

Activated charcoal has been increasing in popularity over the years among pond owners. It can help reduce the number of organic pollutants from pond water that could potentially harm the fish living in the pond. So, how do you use activated charcoal in your pond filter?

Generally, the newer models of pond filters will come with a built-in section for activated charcoal and will come with directions on how to replace the charcoal inside the filter. The filter will usually have a separate section at the bottom that can be removed.

This is where you will place the activated charcoal in the filter. The dosage of the charcoal will depend on the model and type of filter you have, but the filter will come with instructions for this. However, the dose is worked out with a simple calculation as a guideline. 

This calculation is 4-6 pounds of activated charcoal per 1000 gallons of water in your pond. If your filter cannot hold the amount of activated charcoal your pond needs, or you are using an older filter model, then there is another method you can use to place activated charcoal in your pond. 

You can place the activated charcoal in a mesh filter bag and place this bag in a location in your pond that has strong water flow or next to your older model filter. If you have a large pond, you might need multiple mesh bags of activated charcoal around your pond to maximize its effectiveness. 

What Does Activated Charcoal Remove From Your Pond?

Activated charcoal is becoming increasingly popular in filtration systems worldwide, especially among people who own ponds that are stocked with fish. Activated charcoal or activated carbon is used to help filter your pond’s water of certain chemicals. 

This chemical filtration refers to the removal of chemicals that have dissolved in your pond’s water that could be harmful to your fish and other life in your pond. These chemicals can generally pass through the biological or mechanical filter media.  

Adding activated charcoal to your filtration system can turn it into a 3-stage filtration system, which is more effective in keeping your pond clean and healthy. But what does activated charcoal help remove from your pond’s water?

Activated charcoal can help remove organic pollutants from your pond, like chlorine, tannins, residue algaecide, excess fish pheromones, pesticides, odors, and more. 

The most common organic pollutant is tannins, which is the brown color in your pond water due to grass, leaves, or bark falling into your pond and decomposing. Tannins will not be removed from your pond by regular filter media, so activated charcoal is a must if this is the problem in your pond.

How Does The Activated Charcoal Work?

So, activated charcoal can help clean your pond’s water, but how does it work? Activated charcoal is a form of carbon covered in small holes known as pores. These pores increase the surface area of the activated charcoal. 

This means that the activated charcoal has a large surface area that the chemicals in the water have contact with, effectively neutralizing the chemical. Any organic substance present in the water will make contact with the activated charcoal and cause a small chemical reaction. 

This leads to the process of adsorption, which is different from absorption. Adsorption is where the ions or molecules of the organic pollutants cling to the surface of the carbon. These organic pollutants will be neutralized and will slowly form a layer over the activated charcoal, so over time, the charcoal will need to be replaced.

Benefits Of Using Activated Charcoal In Your Pond Filter

Activated charcoal can be used in your pond pretty easily. You can add it to your filter, or if you don’t have a filter capable of taking activated charcoal, don’t worry, as you can still use activated charcoal in your pond.

You can place the charcoal in a double layer of mesh and tie the mesh so the charcoal stays in place. Rinse the mesh off with a bucket of pond water and place the mesh in a location of your pond that has a high water flow. 

If you do this, your pond will still reap the benefits of activated charcoal. But what are the benefits of using activated charcoal in your pond? There are many benefits that can convince you to start using activated charcoal in your pond, whether in the filter or by other means. So, let’s go through these benefits. 

Keeps Your Pond’s Water Clear

Using activated charcoal in your pond will help keep your pond clear as it removes the tannins from the water that causes the discoloration of your pond. This is one of the reasons people start using activated charcoal in their ponds, as regular filters won’t help with this problem. 

Tannins are the organic color pollutants that perforate from organic debris that has fallen into your ponds, such as pollen, grass, and leaves. These color pollutants build up over time and stain your pond water brown. 

Tannins can be difficult to remove from your pond’s water, especially if the levels have built up extremely high. Before activated charcoal was found to help with this problem, you needed to do a complete water change to get your pond’s water clear again. 

However, now that we have activated charcoal, you can avoid all the possible problems that come with a complete water change and still help your pond’s water clear up. 

Helps Improve Fish Health And Growth

Activated charcoal can help with fish’s overall health and growth in your pond. Fish naturally release many different pheromones as they grow and develop into adults. If your pond is stocked with fish, all the pheromones that are left in the water can reduce the growth of the fish you have in your pond and any new fish you introduce.

Activated charcoal can remove and neutralize these pheromones in the pond’s water, bringing the levels of these pheromones back down to a reasonable level. The activated charcoal that you add to your pond can also reduce any harmful substances that are in the water that could make your fish sick or affect their overall health. 

Removes Harmful Substances From The Water

Activated charcoal easily helps clear your pond of organic pollutants that your mechanical or biological filter cannot remove. If you have treated your pond with any medications, pesticides, or algaecides and you are concerned that there is still residue from these treatments in your pond, activated charcoal can help give you peace of mind.

Activated charcoal can remove any residue in your pond that is left behind by all these treatments. Even if you don’t use treatments like pesticides or insecticides directly in your pond but use them in your garden, they can travel through the air and land in your pond, dissolving in the water. 

So, using activated charcoal in your pond can help reduce any unwanted chemicals that have accidentally ended up in your pond.

Reduces Odors And Smells Coming For Your Pond

Using activated charcoal in your pond can also help reduce the smells and odors coming from your pond, which can be unpleasant, especially when the smells begin to build up over time. These smells and odors are generally caused by an imbalance of organic substances diluted in your pond’s water.

One of the most common organic substances that can cause your pond to smell is a build-up of sulfates in the water. This organic pollutant causes your pond to have a smell similar to sewage, and it’s usually caused by the build-up of bottom sludge in your pond. 

Adding activated charcoal to your pond can help reduce these smells over time, making working in your pond a more pleasant experience. 

Considerations When Using Activated Charcoal In Your Pond Filter

Even though activated charcoal offers many great benefits to your pond and helps keep your pond clean, there are things you should know about activated charcoal before you use it in your pond. 

Activated charcoal is highly effective at its job of neutralizing organic pollutants in the water. This can be a good thing, but the activated charcoal can interfere with any treatments you give to the fish in your pond. 

The activated charcoal can effectively remove any medications you add to your pond to treat your fish. Activated charcoal can also reduce or hinder the effectiveness of all pond water dye products and algaecides.

If you are treating your fish for anything, or you are treating an algae problem in your pond, it would be best to wait until these treatments are done before placing activated charcoal in your pond filter. 

What Activated Charcoal Won’t Help With In Your Pond

Even though activated charcoal is extremely good at filtering organic pollutants from your pond water, there are a few things that activated charcoal won’t help with. So, if you are struggling with the following problems in your pond, activated charcoal is not the solution. 

Algae Bloom In Your Pond

If your pond is green due to an overgrowth of algae in the water, activated charcoal will not be able to fix this problem on its own. Activated charcoal can help reduce the organic substances that help the algae grow faster in your pond, but it cannot stop the algae from growing or even spreading to other areas of your pond. 

If you are struggling with algae, a better solution would be to use an algaecide treatment or a UV water clarifier. 

The Source Of The Chemicals In Your Pond

The activated charcoal you place in your pond can help neutralize the chemicals that have made their way into your pond, but they will not remove the source of the chemical pollutants in the water. 

So, if you don’t locate and remove the source of the pollutants, as soon as you stop using the activated charcoal in your pond, the pollutants will build up again and cause the same problems you were fighting. 

How Often Should You Replace The Activated Charcoal?

If you are using high-quality activated charcoal to filter your pond water, you should only need to replace the activated charcoal once every two to three months. This will give the charcoal enough time to use its entire surface area to neutralize the organic pollutants in the water. 

Suppose you don’t replace the activated charcoal in time, and the charcoal has further contact with organic pollutants. In that case, this can cause the surface material of the charcoal to break off and re-enter your pond.

Is Activated Charcoal Good For Pond Filter?

Activated charcoal will not damage your pond filter, especially if your pond filter is a newer model that is designed to hold activated charcoal. If your filter is an older model and doesn’t have a section for activated charcoal, it’s not advised to try and alter your filter to accommodate the charcoal. 

Rather use the mesh filter bag method mentioned earlier and place the charcoal next to or behind your current filter. The charcoal will not damage your filter in any way as it will only help filter the water, even more to help clear it of smaller molecules that the regular filter could not catch. 


Activated charcoal is a great way to help clean your pond and keep the water clear, as it helps reduce the organic pollutants in the water. You won’t be able to place the activated charcoal in your filter unless you use a newer filter model.

Older filter models don’t usually have a section for activated charcoal, as it’s a relatively new product in pond care. However, you can still use activated charcoal by placing it in a mesh filter bag and putting it in a location with high water flow. Good luck clearing your pond with activated charcoal!


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