Hi all -
Since opening my pool this year (last week) the filter has been running funny. At startup it runs normally, low (5-8psi) pressure, good flow from all three return jets. Within about 20-30 minutes, however, the pressure has risen to around 25 psi and the flow to the returns has dropped to almost zero. Looking in the filter basket on the pump it's about 1/2 empty. As soon as I turn the pump off, water rushes back into it from the filter. If I then backwash it for a few minutes, and restart, the pattern will repeat -- it runs fine, though the pressure rises visibly, until around 20 minutes when the flow drops to near zero and the pressure stabilizes at around 25psi.
At this point I've run backwash/rinse (what IS the difference there?) enough that there's no DE left in the filter. Or at least none that can be removed by backwash. The check glass is clean on the backwash when I start and end it. The baskets on the skimmers and in the pump are clean.
I also have a valve that splits the lines from the skimmers and the drain at the bottom of the pool and checked both ways with the same result. It doesn't look like it's struggling to bring water in, anyway, it looks more like it's struggling to push it through the filter.
The outflow side of the filter has an inline chlorinator on it, and I've tried it with it turned to max as well as turned to off without a change.
Any ideas? Should I pop the cover off the filter and see if maybe something is dislodged? Seems weird though given that it works perfectly fine for at least a little while whenever I backwash and restart it.
Appreciate the help TFPers!