Pool Filter Size Calculator

How It Works

Your pool filter is the heart of your water clarity system. The three types differ in filtration fineness: sand filters catch particles down to 20-40 microns, cartridge filters catch 10-15 microns, and DE (diatomaceous earth) filters catch 2-5 microns. The filter must be sized to handle your pump flow rate without excessive pressure. An undersized filter creates high pressure, reduces flow, and needs cleaning too frequently. A larger filter always better — it provides lower pressure, longer cleaning intervals, and better water quality. Cartridge filters are the most popular for residential pools because they require no backwashing, saving water.