Tap to Read ➤

Aquarium Activated Carbon

Ashwini Kulkarni Sule May 10, 2019
Aquarium activated carbon is often used as a filter to control the level of waste in an aquarium. Let's see what this carbon is, the duration it can be used for, and the problems involved with its usage.
Activated carbon is obtained by burning carbonized base material like charcoal or coconut shell, anaerobically. The resulting substance is then subjected to steam, which increases its pore size. This results in the formation of active carbon which has a large surface area.
The surface area is so large that 1 tsp is enough to cover an entire football field. Activated carbon possesses the property of adsorption, due to which impurities cling to its surface.
Adsorption is different from absorption, in which the base material entirely absorbs the other material, while adsorption takes place on the surface of the base material. This property is of great use for the purpose of filtration. Using it in an aquarium is a great idea to eliminate organic waste materials from the aquarium.

Materials Adsorbed

Activated carbon is capable of adsorbing a range of materials including organic as well as chemical waste. The reason why an activated carbon filter is suitable for an aquarium is that it can eliminate large proportions of dissolved organic molecules from the water. It is also capable of removing medications, dyes, and other chemicals from the water.
Although this property can be of great use for removing excess of these materials, it may prove to be a hindrance during the treatment phase in the aquarium. At such times, it is best to remove the carbon filter from the aquarium. Chlorine, chloramine, and heavy metals are some other materials that can be successfully removed from the aquarium.
However, there are certain materials which cannot be removed by this carbon filter which include, ammonia, nitrites, and nitrates. Substances like phosphate, and inorganic salts like sodium chloride, cannot be adsorbed by the carbon either.

Quantity and Duration of Usage

There are no specific recommendations regarding the quantity of activated carbon and the length of time for which it should be used. The reason is that there are many factors which influence these two parameters. Firstly, every aquarium is different with a difference in their biological load.
Secondly, the quality of the carbon often decides the time for the intended usage. Lastly, the life of the carbon filter also depends upon the adsorptive materials it has been subjected to. Some manufacturers may give vague guidelines regarding the duration for which activated carbon can be used.
Carbon pads and carbon sponges can be used for one to four weeks. High quality activated carbon in granular form can be used for several weeks. It is advised not to exceed the carbon filter usage over 3 months.


The use of this carbon filter for aquariums is highly controversial due to certain issues. The inability of carbon filters to use some vital pollutants from water is one of its disadvantages. On the other hand, the carbon filter may remove some essential elements from the water which can be detrimental to the aquatic life.
However, this is unlikely to happen in normal circumstances. If the carbon pad has not been changed for a long time, then chances are that the adsorbed materials might leach back into the water.
However, certain pH conditions are required to stimulate this. Some of these problems can be alleviated by regularly changing your carbon pads, thereby preventing coating or biofilming.
The decision regarding the usage of aquarium activated carbon is entirely yours. There are certainly some benefits of using it, however, if you regularly change the water of your aquarium, you can do without a carbon filter. You can always use a carbon filter for your aquarium whenever required, rather than using it all the time.