High pump pressure

[Darla]

Pressure valve on pump is running at 30 psi but no flow to pool . if i backwash get good flow to pool for only 1 to 2 minutes. Just replaced all new grids that didnt help still have same problem checked impeller not blockage what should we do now

[DevinPool]

I have a Hayward DE Filter, and last year my pool filter ran fine and I only had to back was it once a week or so. After opening the pool myself, the filter withh either go from 10PSI to 20PSI - where the outflow becomes about nill - in a few minutes, or sometimes after an hour. I have taken the filter out and sprayed it down with a hose at high pressure 3 times, and made sure nothing else was in the bottom of the filter container that could be blocking it. Yet, after running for an hour or so, eventually the pressure creeps up and becomes to great to make the filter run and the outflow stops. What else could I check for or what could be causing this? When I use my vacuum for the pool bottom the pressure goes from 12PSI to over 20PSI in less than 10 minutes.

[Joe T]

My Hayward sand filter, installed last summer (2011), is also running at about 30 psi. Usual running pressure is 15 psi and I backwash at 20psi. Is this a clogging problem? I did run it continuously for a couple of weeks with a very dirty (mostly algae) pool.