When water passes through a cartridge filter, dirt is screened out at the surface of the cartridge element. When clean, the element will trap larger particles, with finer particles being filtered out as the pores of the element become clogged by the larger debris.
Cartridge filters have a greater surface area than sand allowing for fewer clogs and easier maintenance. Cartridge filters are designed to run at lower pressure than sand which puts less back pressure on the pump, providing more flow and turnover. Cartridge filters should be cleaned once or twice a season by simply hosing them off. Cartridge element filters trap debris as small as 10 to 15 microns.