Where do I Put Activated Carbon In My Aquarium?

Activated charcoal for Aquarium

Activated carbon is a filtering media used in aquariums to remove odours, organic compounds, and other substances that build up in the aquarium. It’s available as granules or activated charcoal, which must be manually added to the tank.

Carbon granules are very common in home aquaria, but you might not know that activated charcoal is just as popular. You can put activated carbon anywhere in your aquarium to improve its filtration and reduce odours.

Activated carbon can be added to almost any part of the aquarium, but we recommend adding it to the substrate. Ensure there are no gaps between the substrate and the rest of the aquarium and no holes in the glass.

You can also add activated carbon to the skimmer, which can also be used for a power filter. You don’t need to add activated carbon if you have an automatic power filter. Although activated carbon will improve the filtration of any filter, you should choose where you want to add it based on the conditions in your aquarium. You can add activated carbon to any part of an aquarium, but you should remember where it most needs extra filtration.

What Is Activated Carbon?

Activated carbon, or activated coal for short, is carbon treated with a chemical process similar to activated clay. Clay is a sedimentary rock composed of positively charged ions that bond with negatively charged impurities in water.

Activated charcoal is used to remove ammonia and other substances from aquarium water. Ammonia is produced when fish poop, kills plants, and discolours the water. Activated charcoal binds with ammonia and other substances in the water, so the water passing through your aquarium is not clouded.

Activated charcoal also removes odours and other impurities, so it’s a great option for your aquarium. However, activated charcoal will not remove dissolved oxygen (DO) from the water.

Why Do You Need Activated Carbon In Your Aquarium?

Using activated carbon in your aquarium will remove organic compounds, odours, and other impurities from the water. It will also remove some of the dissolved oxygen from the water.

That last benefit is why activated charcoal is used in medical tanks and oxygenated greenhouses. Aquaria often contain hydrogen sulfide (H2S) that can be toxic to fish. By removing some of the dissolved oxygen, you can also remove some of the H2S.

If your aquarium water is heavily polluted, you should also add activated carbon to your aquarium. This will help clean up the water, but it will also starve the plants and aquatic organisms living in your aquarium.

How Can I Use Activated Carbon In an Aquarium?

Activated carbon is a valuable tool for maintaining a healthy aquarium. However, using it correctly and following the recommended dosage and replacement schedule is important. With proper use, activated carbon can help keep your aquarium clean, clear, and healthy.

Step 1: Choose the Right Type of Activated Carbon

There are different types of activated carbon available in the market. The most common types are granular activated carbon (GAC) and pelletized activated carbon (PAC). GAC is more effective in removing impurities and toxins, but it can be messy and requires more maintenance.

PAC is easier to handle and maintain, but it is less effective. Choose the type of activated carbon that suits your aquarium’s needs.

Step 2: Prepare the Activated Carbon

Before using activated carbon, it needs to be prepared to remove any dust or debris that may be present.

Rinse the activated carbon in a bucket of clean water until the water runs clear. This will prevent any debris from entering the aquarium and clouding the water.

Step 3: Choose the Right Placement

Activated carbon can be placed in different parts of the aquarium, such as the filter, a filter media bag, or a powerhead. The best placement for activated carbon depends on the type of aquarium and filtration system.

For example, if you have a canister filter, you can place the activated carbon in the filter’s media basket. If you have a hang-on-back filter, place the activated carbon in a filter media bag and hang it on the filter.

Step 4: Install the Activated Carbon

Once you have chosen the right placement, install the activated carbon in the aquarium. If you use a filter media bag, fill it with the prepared activated carbon, place it in the filter, or hang it on it.

If you are using a powerhead, place the activated carbon in a mesh bag and attach it to the powerhead’s intake. Place the activated carbon in the filter’s media basket according to the manufacturer’s instructions if you use a canister filter.

Step 5: Monitor and Replace the Activated Carbon

Activated carbon has a lifespan of 4 to 6 weeks, after which it becomes less effective in removing impurities and toxins from the water. Therefore, monitoring the activated carbon’s lifespan and replacing it regularly is essential.

You can do this by marking the installation date on your calendar and setting reminders to replace it every 4 to 6 weeks. When replacing the activated carbon, rinse the new activated carbon in a bucket of clean water before installing it.

Tools Needed for Successful Installation

  • Bucket: A bucket is needed to prepare and rinse the activated carbon before installation.
  • Filter Media Bag: A filter media bag is essential for using activated carbon in a hang-on-back filter or a powerhead.
  • Mesh Bag: A mesh bag is needed to place the activated carbon in a powerhead.
  • Canister Filter Media Basket: A canister filter media basket is required to use activated carbon in a canister filter.
  • Calendar or Reminder App: A calendar or reminder app can help you track when to replace the activated carbon.

What Are The Pros and Cons of Using Activated Carbon in Your Aquarium?

Activated carbon absorbs odours and other impurities from the water. It can also remove excess chlorine and chloramine from tap water. It’s very easy to use. Pour the granules into the tank and break them up.

The activated carbon will collect any odours and impurities in the water. It’s safe for plants. Aquaria are often heavily polluted, and activated carbon can reduce the amount of H2S in the water, which is not dangerous to aquatic life. It’s very cost-effective. –  Aquaria that use activated carbon is very cost-effective.

Activated carbon must be added to the aquarium manually, which can be inconvenient. It’s not as efficient as other types of filtration. While activated carbon does a good job of removing impurities, it doesn’t remove as much water as a power filter.

It’s not ideal for marine aquaria. Power filters are required for marine aquaria, but activated carbon is suitable for fresh or saltwater aquariums.

How Long Does Activated Carbon Last in Aquariums?

Activated carbon is a substance that has been through an intense heating and filtering process. From then on, it will be stable and able to stay in your aquarium without breaking down over time. Thus, the activated carbon lasts in your aquarium for as long as you keep it.

You can keep the activated carbon until the day you find a way to get rid of it without using dangerous or harmful chemicals. This means that activated carbon in an aquarium does not have an expiration date like any other consumable product.

How long does activated carbon last? That depends on several factors, such as storage conditions, usage frequency, and storage duration. Please keep reading to learn more about these factors and their effects on the shelf life of activated carbon in your aquarium.

Will Activated Carbon Clear Cloudy Water?

Yes. Activated carbon will remove organic waste from your aquarium water and inorganic contaminants such as heavy metals, chlorine, and even medications from your aquarium water. You can use it as a cloud-buster or algae remover.

Your carbon will also remove the yellowing of your water caused by medicines and medications from your fish. Therefore, once you add activated carbon to your aquarium, you will see an improvement in your water quality.

How Often Should You Change Carbon in the Aquarium?

The frequency of changing carbon depends on how much water you are filtering. The normal water change rate is 25-50% per week. The change rate should not be too slow or too fast. Too fast a change rate will allow the build-up of organic waste in the aquarium, which can harm your fish.

Too slow a change rate will result in carbon that has lost its filtering capacity. It would help if you aimed to have clean and filtered water in your aquarium. It is not ideal to have stagnant water, as this could be a sign that your aquarium filter is failing.

Can You Use Activated Carbon as a Substrate?

Because of its high porosity and adsorption properties, activated carbon can be an effective substrate for some applications. In horticulture, activated carbon can be used as a component of soil mixes or as a standalone substrate for growing container plants.

One advantage of using activated carbon as a substrate is its ability to adsorb excess nutrients and other compounds that can harm plants. This can help to maintain a healthy balance of nutrients and prevent over-fertilization.

In aquaponics, activated carbon can be used as a biological filter medium to remove organic and inorganic compounds from the water. The high surface area of the activated carbon provides a large surface area for the growth of beneficial bacteria, which can break down and convert organic matter into nitrates that plants can use as a nutrient source.


Activated carbon can be used to remove odours from your aquarium, reduce the amount of chlorine in the water and remove excess hydrogen sulfide. The carbon is safe for plants and will not harm your aquatic life.

It’s also very cost-effective and easy to use. However, you must add it to the aquarium manually, it doesn’t remove as much water as a power filter, and it’s not ideal for marine aquaria. Adding activated carbon is a great option if you have an aquarium that needs to be filtered.

Written by Justin Michaels