Cecil, I have a check valve in the line underwater to keep water from backing up and freezing near the surface if we lose power, which happens alot up at the cabin.
So you're saying water could come up and freeze then without a check valve? I always use them with the stones if I have them. Even with the rubber membrane although I've been told it's not necessary with them. Unfortunately I don't have one right now on one of the ponds. Hopefully if I have a power outage the water won't come up to the ice level as the pond bank is quite steep.
What determines the level the water will come up to?
