Pool Filter Cleaning: Sand, Cartridge, and DE

Your filter is the other half of water quality. Chemistry sanitizes, filter removes. Skip filter maintenance and you'll have cloudy water no matter how perfect your chemistry is. Here's how to clean each filter type and how often.

The pressure-gauge rule

Regardless of type, your filter needs service when the pressure gauge reads 8–10 psi above the clean baseline. Write the clean baseline on the gauge itself with a permanent marker when you first install (or after deep cleaning) so you always have the reference.

Sand filters

Weekly: Check pressure. Nothing else.
When pressure is high: Backwash (2–3 minutes until sight glass runs clear), then rinse (30 seconds), then return to filter.
Annually: Deep clean with a filter cleaner that strips oils off the sand.
Every 5–7 years: Replace the sand. It wears down and stops filtering.

Cartridge filters

Weekly: Check pressure.
When pressure is high: Pull the cartridge, hose it off with a garden nozzle from the outside in. 10–15 minutes.
Every 3–6 months:Soak cartridge overnight in a filter-cleaning solution (sometimes called “chemical soak” or “filter cleaner”). This strips oils and fine contaminants a hose can't remove.
Every 2–3 years: Replace cartridge. Pleats wear, efficiency drops.

DE (diatomaceous earth) filters

Weekly: Check pressure.
When pressure is high: Backwash (like a sand filter), then rechargeby adding fresh DE through the skimmer (amount depends on filter size — check the label).
Annually: Full breakdown: open the filter, pull the grids, hose them down, chemical-soak if needed. 1–2 hours.

Which filter wins?

Florida water conservation angle

Cartridge filters don't backwash. You don't waste water every time you service them. In a region with water restrictions during drought, that matters. We install cartridge on most new residential pools.