Do it when the pressure is 8–10 psi above normal. Do it after a massive storm dumped leaves in your pool. Do it if the water flow from the return jets feels weak, like a tired handshake.
But don’t backwash every day out of boredom. Sand filters need their biological “dirty” layer to actually catch small particles. Over-washing makes the water cloudy. It’s like washing your cast-iron skillet with soap—you’re ruining the magic film.
A Note On “Deep Cleaning” The Sand
Every few years, the sand itself gets old and crusty. You’ll know when backwashing barely improves the pressure. That’s when you need to replace the sand. It’s messy, it’s dusty, and it requires a shop vac. Mark it on your calendar as “The Annual Sand Apocalypse.”
But for now, you’ve backwashed. Your filter is breathing again. Your pool is sparkling. Go reward yourself by floating on a raft and pretending you’re a majestic sea turtle. You’ve earned it.
