A Diatomaceous Earth (DE) filter is the most effective type of filter system. DE which is a natural fine powder, coats the filter tank's inside elements. Body oils, suntan lotions, pollens, dust and bacteria are caught in the DE element, leaving sparkling clear, healthier water. As the water is filtered and the DE inside the tank gets dirty, the tank needs to be emptied and both the inside element and tank need to be rinsed before new DE is added.
- DE 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.
- DE filters are "charged" by adding DE powder, usually poured through the skimmer with the filter running.
- DE filters have internal elements that become coated with DE. It is this 'filter cake' that strains dirt, dust, algae, and some forms of bacteria from the water.
- DE filters require more maintenance than some other filters but you get much better filtration. Sand filters will clean to the visible eye; DE filters clean microscopic debris.
- The inside element of the tank must be rinsed periodically (perhaps once a week, depending on swimmer load and environmental factors) and chemically cleaned about once a month.
- The indication this needs to be done is seen from the pressure on the gauge or from a weaker flow of water returning to the pool.
- After a DE filter has been backwashed or drained, a new DE "charge" is added.