Here in SC we have had about 2 weeks of freezing temps. Most days it gets into the mid 30's to mid 40's. My pool filter usually reads about 17 psi normally when pump is on high. I have been running pump on high 24/7 to prevent any freezing in my lines, but I've just noticed 2 days ago (don't always look at the filter gauge every day), that the pressure is up close to 30. I've backwashed several times, and the pressure remains the same.
Could it be that water is frozen in part of my filter, causing pressure to go up? My pool water temps have been in the upper 30's, so that doesn't seem likely, and like I said, my pump runs constantly, but I cannot think of any other reason my filter gauge would be reading so high.
All my returns are open as normal, the pump and filter are 4 years old (sand filter), and I use BBB method. I replaced the filter gauge about a year ago, and I know they easily malfunction, but would it read higher than normal?