Filter Info

Sand is the oldest and most popular method of filtration. Sand filters share two things in common:

1. When in the filtration mode, water always flows from top to bottom
2. They all have some sort of lateral or under drain with slots to hold back sand while allowing clean, filtered water to pass through.

High-rate 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 separate particles, allowing filtration to take place. They operate on the basis of "depth" filtration where dirt is driven through the sand bed and trapped in the spaces between the sand particles. Initially, a clean sand bed removes larger particles, and then, as the bed starts to load up with dirt, the filter removes finer particles. The sand can be cleaned by backwashing which involves reversing water flow through the filter to the "waste" line.

Cartridge filtration has been available for a relatively long time, but has only recently begun to enjoy rapid growth and acceptance.

When water passes through a cartridge filter, 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.

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. 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.

Similar to sand filters, when D.E. filters become dirty, they are 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. For sparkling, clean pools; step up to Hayward D.E. filters.