How often should you clean a pool filter?
Updated July 2026
Rinse a cartridge pool filter every 2–6 weeks, backwash a sand or DE filter when the pressure gauge climbs 8–10 psi above its clean reading, and give cartridges a chemical deep-soak every 3–6 months. The gauge, not the calendar, is your real cue: rising pressure with weak returns is the filter telling you flow has dropped. Stay ahead of it and the water stays clear; fall behind and cloudy water, then algae, is what follows.
What changes the interval
| Your situation | Interval | Why |
|---|---|---|
| Cartridge filter | Rinse every 2–6 weeks | Hose the pleats whenever flow drops or pressure rises |
| Sand filter | Backwash at 8–10 psi over clean | Reverse the flow to flush trapped dirt to waste |
| DE filter | Backwash and recharge at 8–10 psi rise | Add fresh DE through the skimmer after each backwash |
| Heavy bather load or after a storm | Clean now | A debris spike clogs the media ahead of schedule |
| Water turning cloudy or green | Clean, then shock | Weak flow lets algae and bacteria get ahead |
| Deep chemical soak (cartridge) | Every 3–6 months | Oils and scale a hose cannot reach need a soak |
The cost of skipping it
What skipping it costs: a clogged filter chokes circulation, so the pump strains and runs hot while the water goes cloudy and then green. An algae bloom is the expensive end: shock, extra chemicals, and days of running the pump, often $150–500 to clear. A pump motor cooked from running against a blocked filter is another $300–800 to replace. A ten-minute rinse heads off both.
How to do it (20–30 minutes · DIY with a hose)
- Shut the pump off and, on a sand or DE filter, turn the multiport valve to Backwash before you touch anything (never move the valve with the pump running).
- For a cartridge, open the housing, lift the cartridge out, and hose it from the top down between every pleat at a 45-degree angle.
- For sand or DE, backwash until the sight glass runs clear (about 2–3 minutes), then Rinse for 30 seconds; recharge a DE filter with fresh DE through the skimmer.
- Note the clean starting pressure on the gauge so you know your 8–10 psi trigger for next time.
- Every 3–6 months, soak cartridges overnight in a filter-cleaner solution to strip the body oils and sunscreen a hose leaves behind.
Knowing the interval is the easy half. OnOtto reminds you at the right interval, and it won't let you snooze it into next year. Tasks persist until they're done, and completing pool filter cleanings schedules the next one automatically.
Put this on autopilot, free for 30 daysFrequently asked questions
What is the difference between rinsing, backwashing, and deep-cleaning?
Rinsing is hosing off a cartridge; backwashing reverses water flow through a sand or DE filter to flush trapped dirt out the waste line. Both are routine and quick. A deep clean is different: cartridges get an overnight soak in filter cleaner to dissolve body oils, sunscreen, and scale a hose leaves behind. Rinsing keeps flow up week to week, while the soak restores the media a few times a season. Sand and DE media get replaced, not soaked.
How do I know when the filter pressure is too high?
Read the gauge right after a cleaning and memorize that clean number, often around 10–15 psi. When it climbs 8–10 psi above that baseline, flow has dropped enough that it is time to clean or backwash. Rising pressure with weak returns means a clogged filter; a sudden pressure drop instead points to a blockage before the pump, like a full skimmer basket or a clogged impeller.
Can I swim while the water is cloudy?
Cloudy water is a swim-at-your-own-risk sign, not just a cosmetic one: if you cannot see the bottom of the deep end, a swimmer in trouble can be invisible, and the haze usually means the sanitizer is losing to algae or bacteria. Clean the filter, balance and shock the water, and run the pump until it clears, often 24–48 hours, before anyone gets back in. Vacuuming to waste speeds it up.
When should I replace the cartridge instead of cleaning it?
If the pressure will not drop back to baseline after a proper deep-soak, or the pleats are frayed, flattened, or torn, the media is spent and cleaning cannot help. Most cartridges last 1–3 years; see how often to replace a pool filter cartridge for the full rundown. Sand gets swapped every 5–7 years, and DE grids less often than that.