I used things I had kicking around and came up with something to try this winter. I used a 3" pipe that's 32" long, half underwater and half above to, hopefully, keep it above the snow and below the ice. I had some blue foam 1" insulation and used 2 layers pressed on the pipe for floatation. To help keep the water column warm, I added some silvered bubble wrap around the pipe, 1 layer below water and 2 layers above, held on with plastic zip ties. Since I had a chunk of 3" foam pipe insulation, I cut it down to fit inside above the water level. I also added a styrofoam plug to the top of the pipe, with a 3/8" hole to let the gasses escape, while holding in some warmth. To keep snow out, there's an elbow pushed on top, that is removable to check and make sure things are working. So far, the ice on our pond has gotten about 10-12" thick, the bottom of the breather pipe is 16" down, with a weight (chunk of rebar) on the bottom to keep it down. I attached an airstone to the inside at the bottom. I'm hoping this will provide enough circulation of "warm" water to keep things clear of ice in this small space.