Diatomaceous earth is mined from the ocean floor and is the fossilized exoskeletons of tiny diatoms. They are used to coat grids in the filter and act as tiny sieves allowing for the removal of debris as small as 2 to 5 microns. Once the DE filter pressure rises, it is backwashed (running water through the filter in reverse) to unload the dirty DE to waste. New DE powder is then added to "recharge" the filter.
