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. Filtering with diatomaceous earth (D.E.) gives you water that really sparkles. That’s because D.E. filters remove the tiniest of contaminants…particles as small as 5 microns (an average grain of sand is 1,000 microns!). Even though these particles can’t be seen individually, collectively they greatly affect water clarity.