Filter systems assist is cleaning the water and maintaining the proper balance in the pool. Remember pools that are healthy are not crystal clear. Out of balance pools (those with excessive cloudiness caused by fish waste, algae, or sediment) can be cleared up with filtration. Two types of filters are available. Mechanical filters are those which trap impurities in a filter medium removing it from circulation in the pool. The filter medium must be periodically removed and cleaned. Biological filters use a bacteria growth which breaks down the waste and cleans the water naturally. Biological filters require minimal maintenance.
Why Biological Filtration?
Biological filtration is a means of using beneficial bacteria to keep pond water clear and of high quality for fish. Fish and other organisms add toxic ammonia to the water which encourages algae growth. The nitrifying bacteria (Nitrosomonas and Nitrobacter) that colonize the filter break down ammonia into nitrite and then into nitrate, thereby detoxifying the water and removing the nutriment for algae. The bacteria occur naturally in the pong and actually live on and in the fish. In most ponds, however, there are not enough bacteria for the fish population and a filter is used to provide a home for additional bacteria which are also added periodically. While algae are beneficial in taking up ammonia, they tend to cause high pH and take up oxygen at night, causing stress for large fish. Algae are controlled naturally with a biological filter.
The pump must operate 24 hours a day, seven days a week. The bacteria will start to die off if deprived for more than 4 hours of their nutriment supplied by the running water.
The key for successful filtration is to keep the filter clean, this ensuring a thriving bacteria colony. Algae and other organic material in the filter will coat the bacteria and choke off their food supply. As the bacteria begin to die off, more ammonia in the water will cause more algae and water conditions will quickly degrade.
The frequency of cleaning depends upon several variables in the pond such as the amount of leaf litter, size of fish population, and pond size and location. In general, the filter should be removed from the pond and all components thoroughly cleaned once a year (winter is best due to low activity of the fish). Inspect the filter every week or so, and if algae or leaf litter have settled on the matting, remove it and wash it off. Each time the netting is cleaned more bacteria should be added.
Nitrate, the end product of the nitrifying bacteria, will accumulate in the pond. While much less toxic to fish than ammonia or nitrite, it is a nitrogen compound and thus food for algae. A one-third water change one a month will flush out the accumulating nitrate. Control the small number of algae attracted to the nitrate with an algaecide.
During the winter, the bacteria will die off naturally due to lack of nutriment. Thus, you should add bacteria at double the normal dosage as soon as your fish become active their winter lethargy. The matting is made of natural fibers and must be replaced after a year or two as the fibers break down.