36500 gal, DE 48▓ ft. filter.
Initially, the pump would drop flow and increase pressure from about 18psi to about 25psi.
Also, there was evidence of air in the pump basket site glass.
Some small bubbles came out from a jet.
things done so far:
1. Replaced ALL pump / motor gaskets, O-rings.
2. Replaced ALL filter grids and checked for obstructions - no obstructions found.
3. Replaced Jandy 3 way Valves with independent ball valves at both inlets (1.5" Kreepy Krauley and 2" Skimmer).
4. Checked capacitor - Good.
5. Checked and cleaned impeller and diffuser.
6. Blew out and vacuumed every line and component with shop-vac - No clogs found.
7. Both baskets are clean.
I added lots shock and an algaecide to kill it (initially ran it in recirculate to get it all in the water).
The pool was green but I can see the bottom now.
After doing all this, the flow is still diminished and the pressure still increases (but now from 12psi to about 22psi).
There is no longer turbulence or bubbles visible in the pumps basket site glass. Water just moves around.
No air bubbles from any of the jets.
Flow will return to normal if:
1. backwash for a few seconds and start to filter again but will last about 1 hour.
2. run in recirculate then filter again.
3. turn the pump off over night.
The pump runs normal "all day and night" if I run it in recirculate - it does not reduce flow.
I AM STUMPED......