DE filter

A DE filter, or "diatomaceous earth" filter, is one that uses skeletons of diatoms as the filtration media. Diatoms are microscopic organisms with tiny porous hard structures in their bodies.

DE is readily available at swimming pool supply houses, since it is regularly used in pool filters.

There are two principle DE filter systems on the market - the "Diatom Filter" made by Vortex - the original in the field, a crude but powerful machine - and the Magnum filters made by Marineland, which were introduced in the early 1980s.

In any DE filter, there is a basic washable insert through which water is pumped. A small quantity of DE is added to the "dirty side", and quickly coats the insert, providing filtering down to one micron.

Such filters are also referred to as "polishing" filters, since they do such a good job of removing, for example, mulm that has been stirred up during a substrate cleaning process.