I've noticed the psi in our Hayward sand filter jumps from 12 to 17 when run for 8 hours. In years past I've never noticed this kind of increase in pressure. Prior to running the filter for 8 hours, I did vacuum the pool which had a little dirt spread throughout the bottom. My water is clear and the pool test is fairly normal. My pool pump does have a slight whine to it which it did not have at closing in October (thinking the ball bearings might be worn) but I don't know if that would have any effect on psi. Below are my recent pool test numbers. Any insight is appreciated.
FC - 6
CC - .4
PH - 7.4
Alk - 70
CH - 200
FC - 6
CC - .4
PH - 7.4
Alk - 70
CH - 200