4 Things to Know About Backwashing Your Pool Filter

Backwash when pressure rises 8–10 psi above clean baseline The only reliable indicator is pressure rise, not a set schedule. Note your pressure after a fresh backwash, then backwash when it climbs 8–10 psi above that.

Backwashing too often wastes water Doing it too often doesn’t clean better and wastes water. Doing it too rarely lets dirty water bypass the sand and flow back into the pool.

Replace sand every 5–7 years Over time, sand gets rounded and channels form, reducing filtration. If your pool stays cloudy or pressure never drops back to baseline, replace the sand sooner.

Use #20 silica sand filled to about two-thirds of the tank Follow the manufacturer’s recommendation for sand type and fill level. Replacing sand is messy but cheaper than buying a new filter.