The pool water:
1. PH is 7.4,
2. Chlorine Cl is 1.5
3. Pressure when sand filter is backwashed and Restarted the pump, will be 13PSI in the sand filter gauge. And at the outlets, the pressure(force of water) will be good
4. Pressure after the recirculating pump runs for about 3 hours will be 22PSI in Sand filter pressure gauge. And at the outlets, the pressure will drop considerably.
When sand filter is put in circulation(by pass), then there is no drop at the outlets. WORKING FINE.
The problem not able to trouble shoot is The drop of pressure at the water outlet after 3 hours of recirculating pump run.
Tried Even after increasing the Sand in the sandfilter.
Tried decreasing the sand in the Sand filter,
Tried even after replacing sand filter.