I have heard for several years about many alternative methods for keeping tank water open in the winter. This year, instead of using a coil heater I am using a bubbler designed for a 150 gallon fish aquarium. It is mounted on a wall in the feed shed with a little hose running about 40 ft. out to the tank. You can't even hear it run unless you are standing right next to it. Right now I have the hose attached to a steel rod to hold it on the bottom of the tank but I am going to get a hold of some small diameter PVC and plumb it up with a few holes in the bottom side of the pipe. It been getting down in the single digits at night and a few Â°'s above freezing during the day. It keeps a 24" hole open on the coldest nights and the ice that does form is only a skim. The surface of the water is moving too much to really freeze solid. It clears any ice before the next evening. I don't believe that this would work as well, in my climate, if I only had a small tank or if the water was shallow. I'm using it in a 500 gallon oval. I'm happy with the results and will see if there are any changes when it gets down below 0Â°F at night.