As you set up your aquarium, one of the first decisions you will need to make is the type of filter you will install. Not only does the type of filter matter, but so does the filter media. Here are the three main types to consider.
Coarse Filter Media
Coarse filter media is some sort of material that traps large pieces of debris and keeps it from returning to the aquarium. Sludge, uneaten food particles, and fish waste products can all be trapped by the coarse filter media. This is sometimes called a mechanical filter. The netting found on many filter cartridges is an example of coarse filter media.
Activated Charcoal or Carbon Filter Media
Activated charcoal or carbon filter media works as a chemical filter for the aquarium. This helps maintain proper water quality over time by filtering out many water pollutants. Activated charcoal or carbon is found in most filter cartridges.
Ammonia Control Filter Media
Ammonia in your fish tank is toxic to your fish. They cannot tolerate much of this at all, yet it is a natural byproduct of their digestive cycle. As a result, many aquarium owners choose a chemical filter that has an ammonia control component. This filter media is made from particles of an ammonia-removing mineral, such as zeolite, that is not harmful to the fish.
The best filtration system will use a combination of these three filter media. In addition, a good filter system will contribute to the biological filtration of the fish tank. This occurs when good bacteria grow on the filter and in the filter media. Like an ammonia control media, these good bacteria help eliminate ammonia in the fish tank, leading to a healthier overall environment for the fish.