Pools and Spa Filters Glossary of Terms

D. E. FILTER

Diatomaceous Earth Filter – A filter designed to use diatomaceous earth (D.E.) as the filter medium. The D.E. is added through the skimmer with the pump on, which takes the D.E. and deposits it on a grid. The D.E. then becomes the filter medium.

DIATOMACEOUS EARTH

Also called D.E. – A white powder composed of fossilized skeletons of one-celled organisms called diatoms. The skeletons are porous and have microscopic spaces. The powder is added through the skimmer with the pump on and deposits itself on a grid. The powder then becomes the filter medium.

FILTER

A device that removes suspended particles from water by recirculating the water through a porous substance (a filter medium or element). The three types of filters used in pools and spas are sand, cartridge and D.E. (diatomaceous earth).

FILTER AREA

The total surface area of the filter medium that is exposed to the flow of water from the pump, expressed in square feet. Examples are: a 36 sq.ft. D.E. filter and a 100 sq.ft. cartridge filter.

FILTER CARTRIDGE

A replaceable porous element made of paper or polyester used as the filter medium in cartridge filters.

FILTER CYCLE

The operating time between cleaning or backwashing cycles of a filter. Also the amount of time the filter has water flowing through it each day expressed in hours.

FILTER MEDIUM

The material used in the filter to trap suspended dirt particles as the water is flowing through it. The polyester or paper used in making a cartridge filter element. The sand used in a sand filter. The D.E. (diatomaceous earth) used in a D.E. filter.

FILTER, SAND

A type of filter media composed of hard, sharp silica, quartz or similar particles with proper grading for size and uniformity. The most common grade used is No. 20 in sand filters.

FILTRATION RATE

The rate at which the water is travelling through the filter, expressed in U.S. gallons per minute (gpm) per square foot of filter area.