The total surface area of the filter medium that is exposed to the flow of water from the pump, expressed in square feet. Examples are: a 36 Sqft. D.E. filter, a 520 Cartridge Filter or a 4.9 Sand Filter.
The effective area, expressed in square feet, through which water approaches the filter media.
The effective area through which water passes through filter media, often expressed in square feet. (See cross sectional area.)
Quantity of filter media available for collection of contaminants. Expressed in square feet.