Equipment

Pool Filter Types Compared: Sand, Cartridge, and DE

The three filter types trade off the same three things differently: filtration fineness, maintenance effort, and upfront/ongoing cost. This site is dedicated to a single build method: gunite (shotcrete) construction, rebar cage, sprayed and hand-finished concrete, engineered bond beams, and a design that can be shaped to anything the lot allows, from tanning ledges to negative edges to integrated spas.

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How Each Type Filters

Sand filters push water through a bed of specially graded sand that traps particles roughly 20-40 microns and larger; they are cleaned by backwashing, which reverses flow to flush trapped debris out to waste.

Cartridge filters use a pleated fabric element that traps particles down to roughly 10-20 microns; they are cleaned by removing the cartridge and hosing it off (or soaking it periodically in a cleaning solution), with no backwash water lost.

DE (diatomaceous earth) filters coat a set of fabric grids with a fine powder made from fossilized diatoms, trapping particles as small as 3-5 microns, the finest filtration of the three; they are also cleaned by backwashing, with fresh DE powder recharged afterward.

Which One Fits Which Situation

Sand filters are the lowest-maintenance and least expensive to operate but offer the coarsest filtration; a reasonable default for a straightforward residential pool without unusual water-clarity demands.

Cartridge filters trade a bit more hands-on cleaning for finer filtration and no backwash water waste, a common upgrade choice. DE filters give the clearest water of the three but need the most attention (periodic DE recharging) and typically cost more to operate; they are most often chosen for pools where water clarity is a priority worth the extra maintenance.

FAQs

How often should a sand filter be backwashed?

When the pressure gauge reads 8-10 psi above the clean, just-backwashed baseline, not on a fixed calendar schedule; backwashing too early wastes water and filter media life.

Does filter type affect how fast chemicals work?

Finer filtration (DE, then cartridge, then sand) removes smaller particles that can shade or interfere with chlorine's effectiveness, so finer filtration can modestly help water clarity and sanitizer efficiency, though chemistry still does the sanitizing work.