Backwash when the pressure gauge says to, not on a calendar.

When the pressure gauge reads 8–10 psi above your clean baseline pressure. Not every week, not every other Tuesday — when the needle tells you.

DE filters work best when the grid is loaded with DE. If you backwash too often, you waste DE and don’t filter as well. If you wait too long, flow drops and pressure spikes. The gauge is the only honest signal.

Ignore the “backwash every X days” advice you see on pool forums. The cloudiness of your water, the amount of debris, and your pump run time all affect how fast the filter loads. In heavy swim season you might need to backwash every few days. In winter maybe once a month. The gauge knows.

Let it be your only meter.