Custom Search


Creating a Balanced Tank with the Right Aquarium Filter Media


aquarium sponge filter

Because aquariums are a closed ecosystem, and often overcrowded, filtration is very important in creating a healthy environment for your fish. Choosing the proper aquarium filter media will help your fish to remain healthy.

When you choose an aquarium filter, you may not give a lot of thought to how they work, or the filter media, which is the part inside the filter that removes the fish waste. It is the filter media that controls how much and what type of filtration that occurs.

There are three types of aquarium filter media, mechanical, biological, and chemical. Often these 3 types can be combined within the same filter to enhance your aquarium filtration capacity. You can find most types of filter media at places such as Swell UK.

Mechanical Filter Media

Mechanical filter media works by removing particles and debris from the water. There are pores in the media that allows water to pass through, but traps the debris. Often this takes the form of filter pads, filter bags, or cartridges. The water passes through the filter pad and uneaten food and other particles are removed from the water before it is returned to the aquarium.

The filter pads or bags must be changed periodically otherwise they fill up with debris and water flow through the filter will decrease.


Biological Filter Media

Biological filtration occurs when nitrifying bacteria present in the tank breaks down fish waste products, such as ammonia, into more harmless substances. This is usually referred to as the nitrogen cycle. These nitrifying bacteria need a proper surface on which to grow and this is where biological media is needed. The media most commonly used for this is ceramic media. These are generally porous to increase the surface area for bacteria to grow on.

Sometimes plastic and foam are also used, however, nitrifying bacteria will build up more quickly on ceramic filter media.

Keep in mind that the bacteria growing on biological media will be killed off if you use antibiotics in the tank.

Chemical Filter Media

Chemical filtration works by removing chemicals and pollutants from the water, including heavy metals. The most common type of chemical media is activated carbon. This has a porous surface and can remove a variety of chemicals from the water. This is why when treating a tank with medication, the instructions will often tell you to remove the activated carbon from your filter. If you leave it in, the activated carbon removes the medicine from the tank as well as the impurities and other toxic substances.

Another common chemical fitration substrate is zeolite, which removes ammonia from your tank.

Chemical filtration is usually the last filtration step, meaning that mechanical and biological fitration take place first.

Chemical filtration media also needs to be changed periodically, otherwise it will become full of toxins and can't hold any more pollutants.

All 3 Methods Combined

Most filtration systems try to combine at least two of these filter media and often all three are used. For example, if you examine the filter media from a common hang-on type aquarium filter, it usually consists of a bag, with actived carbon inside. The bag itself serves as the mechanical filtration and the carbon serves as the chemical fitration. Often these filters will also contain some sort of media for the bacteria to grow on. In fact, some nitrifying bacteria will even grow on the filter bag itself.

By using all three types of filter media, and performing weekly partial water changes, you should maintain a healthy ecosystem for your tank.