Diatomaceous Earth (D.E.) filters are the most efficient filter for your pool and will remove particles from 3 to 5 microns in size. To give you an example of how small a particle the D.E. filter can remove, a 4 micron particle is 12 times smaller than the smallest particle visible to the human eye. D.E. or diatomaceous earth is the media for the filter. The media is composed of fossilized remains of a microscopic algae that are several million years old. Called diatoms, these fossilized exoskeletons are very porous which gives them significant filtration capacity. Once mined, they are processed into a fine powder and used as a precoat media on the fingers or grids of your filter. The primary function of the fingers or grids is to provide a surface and structure to allow filtration to take place. Do not operate a D.E. filter without the media on the fingers and grids. Also, the correct amount of media applied to the fingers and grids are important too. The specification tag on the side of the filter will indicate the correct amount of D.E. to be applied for each cycle.
There is also a replacement filtration media called Fiber Clear for D.E. filters. It is made from 100% biodegradable cellulose fiber. This media performs equally well or sometimes better than D.E. The major advantage of cellulose media is that it is biodegradable and you use less product per cycle. The cellulose media can also be applied to sand and cartridge filters to improve efficiency when the pool water has a persistent cloudy condition.