My pool is 5 months old, I have a Jandy CL340 cart filter. There is a gauge on the top for the pressure. It also indicates clean and dirty arrows. When the pool was new the PB set the clean to about 9psi and the dirty arrow is at about 20 psi. The pool has always run at the 9psi when the pumps are on but jumps to about 21psi when I turn the vales to the spa. Never any problems.
Like I said, its been 5 months and I expected the psi arrow to reach the dirty mark indicating time to clean the filters. Never moved off of 9psi still in the clean area. Well, I have noticed a lot of dirt on the bottom after the pumps stop, so I took apart the filter for the first time to clean them. All 4 were coated with sand and mud, totally filthy. Cleaned them all and they looked new, nice and white. Put everything back together and still, the psi was 9 and when I switch to the spa it goes up to 21 psi.
The questions is, why did the psi gauge never go up as the filters got dirty? And, why does the psi go up so high when I switch the vales to the spa?