Hayward Diatomaceous Earth (D.E.) Filters
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 during the first pass through the media.

All D.E. 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.

Similiar to sand filters, when a D.E. filter becomes dirty, it is cleaned either by backwashing, or regenerating and draining, the clogged D.E. to the 'waste' line. To restore filtration, a fresh 'charge' of D.E. is added to the filter.