I moved into this place 2 years ago, and the pool is 30 years old. I assume the sand filter is quite old, and have no idea when or if the sand has been changed.
My PSI usually runs at 15, and almost never moves off of that mark no matter what, if I leave it alone. Sometimes after I vaccum the pressure stays down at 10 or 11 PSI, where it was during the vacuum process. Then after Ibackwash, it goes back to 15. It is like my PSI goes in reverse, increasing after a backwash rather than decreasing.
Also, I suspect I am getting some very fine dust like material returned to the pool via the jets, as a couple hours after I vacuum spotless, I begin to see a small build up of the fine stuff.
Lastly, I have a suction side leak causing air bubbles in the pump basket and throught the return jets. Pum is new last year, and the lid is not the problem. How important is it to have this fixed?