The efficiency (square feet (sq.ft.) of surface area per cubic foot (cu.ft.)) of each material is easy to determine from the table above. The volume of material used in a particular system will be determined by the filter design.
Unfortunately with increased efficiency comes greater maintenance. The smaller the channels through the material, the more solid material (food, detritus, etc.) will be stopped, blocking water flow and reducing efficiency. In general, the higher the efficiency of the material, the more easily the material will clog, with sand and carbon being the worst offenders. Any bio-material can be cleaned.
Passing the water through a good mechanical filter before it reaches the biological filter media is highly recommended, as this will greatly reduce maintenance on any material, but inevitably, the material will need to be cleaned. Cleaning the bio-material will dislodge a certain amount of the resident bacteria, along with the clogging foreign material. This will temporarily (until bacteria can repopulate) reduce the bacteria population and the capacity of the biological filter to convert ammonia to nitrates. Since we don't want to reduce the bacteria level to a point where ammonia spikes occur and unprocessed nitrites become evident, cleaning the bio-material should be performed in steps. Periodically cleaning only a portion of the material before reinstalling it in the filter will help avoid a catastrophic reduction in biological filtration.
