Sand Swimming Pool Filters – Filter Range 20 to 40 microns. The oldest and most popular method of filtrations is sand. Sand filters use a special filter sand, normally .45 to .55 mm (also known as pool-grade #20 silica sand), because it has sharp edges that serve to separate particles, allowing filtration to take place. Sand filters are the least expensive of the three types of filters but only filters particles down to 20 to 40 microns in size.

Cartridge Swimming Pool Filters – Filter Range 10 to 20 microns. Cartridge filtration has been available for a relatively long time, and recently has begun to enjoy rapid growth and acceptance. When water passes through cartridge swimming pool filters, dirt is screened out at the surface of the cartridge element. When clean, the element will trap larger particles, with finer particles being filtered out as the pores of the element become clogged by the larger debris. The cartridge element can be removed and cleaned by pressure washing inside and out with a garden hose.

D.E. (Diatomaceous Earth) Swimming Pool Filters – Filtration Range 1 to 3 microns. Many pool professionals consider D.E. filtration to be the finest, because it is capable of removing smaller particles than either sand or cartridge. Diatomaceous earth is a porous powder with microscopic openings, that, when magnified, look like tiny sponges. Clear water can pass through these openings but particles, as small as one to three microns are trapped the first pass through the media. All D.E. swimming pool filters have internal elements that become coated with D.E. It is this “filter cake” that strains dirt, dust, algae and some forms of bacteria from the water. Similar to sand swimming pool filters, when a D.E. filter becomes dirty, it is cleaned either by backwashing the clogged D.E. to the “waste” line or regenerating and draining. To restore filtration, a fresh “charge” of D.E. is added to the filter.

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