I think this discussion was talked about in 2010. But like to get a new response!
I have a Hayward 48sf DE filter. PB suggested to backwash every month and clean twice a year. When I cleaned my filter for the first time in Sept.2013, psi gauge indicates 25psi after cleaned. Also when I backwash monthly, it also indicates 25 psi after backwashed. I had this pool now about 9 mo. and every month the psi gauge indicates 27 psi, only 2 psi increase a month.
(25 psi x 25% = 32 psi) Should I just wait till I see 32 psi before backwash and continue to clean twice a year? I think I'm just wasting money on DE powder... Thanks