Backwash when pressure climbs 10 psi over clean.

Every time the pressure gauge reads 10 psi above your clean baseline. That’s it. Not once a week. Not when the water looks cloudy. When the pressure tells you.

Here’s the simple process:

Turn off the pump. Slide the multiport valve to BACKWASH. Turn the pump back on. Let it run until the sight glass runs clear (usually 1-2 minutes). Turn off pump, move valve to RINSE, run for 30 seconds, turn off again. Then set valve to FILTER, turn pump back on, and — this is the DE-specific part — add fresh DE through the skimmer. Exactly how much? The amount printed on the filter label. Usually 1-2 lbs for a new charge, then about 80% of that after each backwash.

When do you do this? Anytime the pressure rises 10 psi above where it was right after you cleaned the grids and added fresh DE. If you don’t remember your clean pressure, write it down next time. Or just backwash whenever the pressure hits that 10-psi bump.

Do not over-backwash. Doing it too often wastes DE and water. Under-backwashing makes the filter work harder and can blow dirty water back into the pool.

It is not as complicated as it sounds.