PF 72sqft Nautilus Plus DE Filter Nautilus® Plus 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. And, the 100% premium-grade stainless steel tank ensures reliable operation for years. Features Maximum Operating Pressure 50 psi Exclusive clamping design is proven to be safe strong and reliable 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 maximum flow when draining filter 2 in. plumbing connections allow for maximum flow