I moved into a house last year that has an in ground pool, the first pool I've owned so I am new to pool care and feeding. The problem I am experiencing is causing the pressure on the gauge attached to the filter to increase from 9 psi to 20 psi sometimes over a few hours and sometimes in a matter of minutes, once the pressure rises there is no flow from the returns, the SWG also displays the message "no flow". Since I opened the pool 2 weeks ago I initially assumed it was due to the filter doing it's job and I would backwash it and the pressure would drop back down to 9 psi and everything was fine again. This continued for the most of the week and didn't seem to be improving even though the water looks fairly clear. I was backwashing the pool about every 2 hours which seemed to me to be excessive so I started looking for other causes.
What I have stumbled upon has me baffled - if I simply turn off the pump for 10-15 seconds the pressure will drop from 20 psi to 9 just as it does when I backwash it. This led me to believe there was some sort of obstruction in the plumbing so I disassembled the plumbing around the filter and pump checked the lines and I didn't find anything. I ran water backwards through the filter valve to see if there was something trapped in there - nothing. The pool has 2 returns which are connected via one valve to the outlet of the filter and fountains that are on a separate valve and when the flow drops both are affected which would indicate to me it's not something underground between the filter and the returns.
At this point I am at a loss for possible solutions. I didn't have any issues with the pool like this last year. I installed the SWG in July of last year about 1/2 way through the season. I think my next logical step would be to disassemble the 6 way valve to look for something that is malfunctioning or clogged but I don't know the manufacturer of the pump or filter and I don't know where I would get replacement parts for it if I were to break something during disassembly, it still sort of works and I could make it worse.
I am looking for suggestions or if anyone has experienced an issue similar to this in the past.