Cartridge filters have a greater surface area than sand allowing for fewer clogs and easier maintenance. They run at lower pressure than sand which puts less backpressure on the pump, providing more flow and turnover. Cartridge filters should be cleaned once or twice a season by simply hosing the cartridge element off. Cartridge element filters trap debris as small as 10 to 15 microns.
Diatomaceous earth (D.E.) is mined and is the fossilized exoskeletons of tiny diatoms. They are used to coat “grids” in the filter housing and act as tiny sieves allowing for the removal of debris as small as 5 microns. Once the pressure rises, the filter is backwashed just like a sand filter and then “recharged” with more D.E. powder. D.E. filters trap debris as small as 2 – 5 microns.
Sand filters in pools are used to extract impurities from the water by utilizing sand to collect debris as tiny as twenty microns. To discharge water waste, the sand filter must be backwashed (i.e., running the filter in reverse).