The Pro Series filter features an integral top diffuser that evenly distributes unfiltered water over the sand media bed in a cascading, umbrella-like pattern. This allows the greatest filtration possible from every square inch of sand. Then the self-cleaning underdrain assembly, with its 360° slotted laterals, provides a fast, balanced flow of clear water back to the pool while allowing for more thorough backwashing. Best of all, the Pro's full-flow technology reduces your energy costs because the filter operates for shorter periods.