Hi! I have the Hayward Pro Grid DE4820 (48 sq ft). My pressure with a fresh charge of DE was 9 psi. After vacuuming, it had climbed to about 20 psi. I shut the pump down for an hour or 2, came back out and restarted the pump, and the pressure was back down to 9 psi again. After more vacuuming, it climbed to 20 psi. Shut down a few hours, restart, and it is back down to 9 psi. It seems to always drop back to the fresh charge pressure after each shut-down (though, it climbs quicker to 20 psi each time as more gunk accumulates in the filter).
Is this normal for DE filters? Any ideas of what's going on?
The filter works great and keeps the pool nice and clear.