Backwash when pressure says so, not on a calendar.

Stop backwashing on a schedule. Your DE filter will tell you when it needs cleaning — listen to the pressure gauge.

Most pool pros recommend backwashing when the pressure rises 8–10 PSI above the clean baseline. That baseline is the pressure reading right after you’ve cleaned and reassembled the filter with fresh DE. Write it down. For example, if your clean pressure is 15 PSI, backwash when it hits 23–25 PSI.

The “every two weeks” advice is lazy. Filters get dirty at different rates depending on how much you run the pump, how many leaves fall in, how many kids splash around. Time-based backwashing either wastes water or lets the filter clog too long.

Other signs: water flow from returns looks weak, the pump runs louder than usual, or you notice cloudy water even after vacuuming. But honestly, the pressure gauge is the most reliable indicator. If you don’t have a working gauge, replace it. They’re cheap.

Trust the gauge, not the calendar.