PF 60sqft FNS DE Filter FNS?® Filters have been designed with curved grids to maximize filtration area. More filter area means better performance and longer periods between cleanings. Our exclusive internal design has been refined to minimize flow restrictions, and therefore requires minimal pumping power to achieve a needed flow rate. That means lower utility costs. Features Maximum Operating Pressure 50 psi Sturdy tank clamp of premium stainless steel has permanent spring mechanism to correctly indicate proper tightness for securing tank halves Water flows in bottom, up and around filter grid for even distribution of diatomaceous earth, eliminating bridging between elements and providing highly efficient filtration Exclusive grid assembly with molded-in handles lifts out easily for inspection and periodic cleaning Backwashes from top to bottom utilizing gravity for complete cleaning of accumulated dirt and D.E. powder 2 in. bottom drain assembly permits unrestricted flow when draining filter 2 in. plumbing connections allow for maximum flow