I have one of these in my pasture where we winter the cows on stockpiled forage and/or swath-grazing. As soon as it gets below -20 C, it's a real chore. We knock the ice off the top twice a day, and if you don't get the line insulated/covered real well where it comes out of the ice to the tank, you have what's known as a certified pain in the @$$.
I rigged up a length of hose with the proper fittings to a Baker pump so we could pump hot water down and blow out ice plugs if it did freeze, but who wants to do that? If there's snow on the ground, we let 'em lick it. This past winter we didn't have very much, so they had to have something.
I worked on a local feedlot a couple years back, and they had just put in 12 or so of those tires. It made for an eventful winter. Even with power to all of them, we had grief, b/c the float would freeze to the tire walls, then the cattle would drink the thing dry by the time you got through all the pen-checking in the morning.