Waterco Micron SM600 - 24" Sand Filter - Side Mount Plumbing

In general terms, you’ll know it’s time to clean your filter when the Filter Pressure, as displayed on the pressure gauge, rises to the threshold recommended by the manufacturer - this is usually 7-10 lbs. above the “clean” pressure. Consequently, there are two key steps:
1) Confirm from your owner’s manual the pressure increase recommended for cleaning, and
2) Make note of your filter pressure when the filter is clean(ed) for reference purposes.

Estimates of filter cartridge lifespan vary widely from 1-2 years to 3-5 years and all points between. Where you might find yourself within those ranges can be influenced by your immediate environment, the square footage of filter media relative to pool size, and the extent to which your pool is subjected to body oils, lotions, hair products, etc. A great way to maximize filter cartridge life is to use a pre-filter which can intercept much of what otherwise reaches your filter cartridges.

The three main categories of pool filters are: DE Filters, Cartridge Filters, and Sand Filters which, respectively, can filter particles as small as 5, 10, and 20 microns. Cartridge Filters are removed from the filter and cleaned with running water and a cleaning solution, if necessary. DE and Sand Filters are subjected to “backwashing” pool water to clean debris from the filter media. This process can commonly take 2-300 gallons of water that will then need replaced, resalinated, and rebalanced. Cartridge Filters are the most water-efficient and are easiest to maintain, while DE filters give you the most effective filtration.