FNS Plus Pool Filters are designed with curved grids to maximize filtration area. More filter area means better performance and longer periods between cleanings. The internal design has been refined to minimize flow restrictions and, therefore, requires minimal pumping power to achieve a needed flow rate. This vertical-grid, D.E. filter is made of fiberglass-reinforced polypropylene for superior strength and reliability. D.E. filters remove the tiniest of contaminants—particles as small as 5 microns (an average grain of sand is 1,000 microns). Just like a sponge, water can pass through, but microscopic impurities like dirt, algae and some forms of bacteria can’t. FNS Plus filters have been designed with curved grids to maximize filtration area. More filter area means better performance and longer periods between cleanings. Our 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.