A quality biological pond filter is an essential piece of equipment necessary to any well-designed filtration system. Biological filtration is a broad term referring to the means of housing beneficial bacteria that are able to clean pond water at a molecular level. In a natural stream or river, bacteria colonize on the stones and pebbles at the bottom of the stream, which naturally break down toxins as the water flows overtop. It is this natural process that manufactured biological filters attempt to emulate. However, instead of cultivating bacteria at the bottom of the pond like in nature, for ease of maintenance, bacteria are colonized in various types of filter media, which are stored in a filter housing outside of the pond. The water is forced to flow through the filter via a pumping system, or a gravity fed system.
Why you need biological filtration?
One of the main uses for a biological pond filter is to convert harmful ammonia, which is toxic to fish and other life, into nitrite and then eventually nitrate. Amonia is naturally produced from fish waste and other decaying matter in a pond. Although nitrate is non-toxic to koi and other pond fish, it is a plant nutrient, which will naturally promote the growth of certain types of algae such as blanketweed. Therefore, it’s a good idea to try to manage the levels of nitrate in your pond. There are a couple ways of dealing with excess nitrate. One way is through the use of a vegetable filter, which is a separate area of the pond filled with moisture-loving plants that will naturally absorb nitrate. Another way is through scheduled partial water changes, which replaces a portion of the pond water with new nitrate-free water.