Vertical Grid DE filters have up-flow filtration, top-down backwashing...and the world's most sparkling water.
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.
High-Rate Sand Filters
Sand filters feature exclusive 360° slotted self-cleaning laterals for total cleaning power
The oldest and most popular method of filtration is sand. 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 underdrain 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 serve to separate particles, allowing filtration to take place. They operate on the basis of "depth" filtration; dirt is driven through the sand bed and trapped in the minute spaces between the particles of sand. Initially, a clean sand bed will remove larger particles, and then, as the bed starts to load up with dirt, it will remove finer particles.
Cleaning of the media, or sand, is accomplished through reversing the flow through the filter, to the "waste" line. This is known as backwashing.
Cartridge filters incorporate unique extruded core element for extra strength and maximum flow
Cartridge filtration has been available for a relatively long time, but only recently has it 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.