Denhoff,ND right in the center of the State | Rich we use large round earthmoveing tires that have a overflow on them, and a 10,000 gallon fiberglass tanks buried underground with submersable pumps that run constantly, bringing up warm water that recirculates and they never freeze, my kids caught a few painted turtles this past summer and threw them in the rubber tanks for pets and they were swimming around in the water all winter so far, been bitter cold here too. We have float on them, and when the tanks below get down the well starts to pump so there is always fresh supply of water, yearly we have man holes and go in the tanks below and clean out. My dad came up with this idea about 30 years ago and has made many of these systems work very well, we always keep a few submersable pumps on hand, dont take a large pump, just something to circulate the water, think they are 1/3 or 1/2 hp. Never had one freeze in 30 years. Terry |