When rainfall results in a water level that must be lowered & your backwash is not yet indicated according to the pressure gauge but is definitely not at the lowest mark/beginning pressure, I assume it is just fine too lower the water via backwash? Are there any good reasons that one should not backwash assuming that the pressure is not at the "beginning pressure"
Unrelated question: my sand filter was new about three years ago. The beginning pressure was always 10 or 12 including at closing last season. This year, the beginning pressure was 20. I have had to backwash three times & the gauge appears to be working normally. Just curious why the beginning pressure would change. It is possible that some minor air leak somewhere no longer exists; the only reason I say that is because the air bubble visible on the top of the pump basket does seem to be a little smaller; maybe I have the cleaner attachment just right and never did before, who knows?