My sand filter is usually 15 to 20 psi. Temps dropped to record lows (single digits) and rolling blackouts have us on power for an hour, power off an hour. I had pump running continuously since the start. My pressure gauge is now pegged...shut off pump goes back to zero...turn on pump goes all the way around to zero. I tried to backwash but nothing happens. This was over the first night. I didnt think water could freeze that fast but I'm thinking maybe water froze in part of the system? Seems like water is still circulating. My filter is overdue for a sand change and had been seeping from the top ring last couple weeks...ok...months. Normally I would backflush and that would do the trick. I'm a little concerned about the pressure let alone trying to do anything to it while it is reading that high. I tried to heat the pipes but didnt work. Appreciate any suggestions