Filtration is an important aspect of fishkeeping for every type of aquarium; freshwater, brackish water and saltwater. All aquariums require filtration and there are three kinds of filtration methods; Chemical filtration, biological filtration and mechanical filtration. The reef aquarium needs all three types. I will discuss all three types of filtration, but biological filtration is the most important type of filtration for a reef aquarium.
Mechanical filtration is the simplest and most visible form of filtration. It is the physical act of removing debris from the aquarium water, rock and substrate (sand). So mechanical filtration is essentially removing the fish feces, uneaten food and other waste from the aquarium water. It is important the debris be removed so that it will not foul the water and threaten the health of the aquarium inhabitants. There are three types of mechanical filtration set ups for you to choose from. You may purchase a mechanical filter that hangs on the back of your aquarium, a canister filter that may be placed on the back of your aquarium or hidden in a cabinet underneath or you may purchase an underwater gravel filter. Be sure to consult your local aquarium store to get a recommendation on the best mechanical filtration system for your aquarium setup.
Chemical Filtration is used to remove dissolved organic compounds from aquarium water. If we think of mechanical filtration as removing debris and the solid particulates that we can see, from the water then chemical filtration is removing the dissolved organic compounds that we can’t see. Contrary to what you may think, chemical filtration doesn’t require the addition of chemicals to the aquarium, it’s basically using activated carbon to attract the chemical. The chemicals are removed from the water because the activated carbon attracts and holds the chemicals by making a chemical bond with the substance. Once the bond is made the undesirable chemicals have been removed from the water. However, because they are adhering to the carbon it will have to be replaced frequently.
Biological filtration is basically about having beneficial bacteria in your aquarium. Good bacterial eliminates nitrogen and phosphorus containing compounds from the water. Nitrogen and phosphorus are the byproducts of metabolism. Biological filtration is the result of good bacteria growth in your aquarium and this takes time.