I have a Hayward S166T sand filter, and the pressure has been erratic over the past 3 weeks, well, since start-up.
I changed the sand about 3 weeks ago before I turned it on for the season.
I started with a bad algae problem and fixed it, although now my water will not clear from a milky white color.
The clean pressure is 5psi, and I never let it get above 12 psi. If it gets to 12 psi I backwash, rinse, and restart.
For the past several days it has been at 5 psi. Then 3 or 4 hours later it will go up to 10 psi for 3 or 4 hours, and then shoot back down to 5 psi.
Any clues as to what this might be?
All of my hoses are tight. The cover o-ring on the pump is new and not letting air in, and the filter head is secure and airtight.