If the bucket de-icer has been ineffective, then you might consider wrapping the bucket with an insulator. The best one I can think of that's non-bulky and not likely to attract pecking is a "space blanket." One side of it reflects heat back toward its source. You'd need to tape or tie it on, and/or use a strap over the top to secure it, but it should reduce heat loss through the sides of the bucket. You could also put a piece of it on the top.I've read most (but I'll admit, not all) of this thread and attempted searching for how these do in sub-zero temperatures. Looks like some of you have used a 60 or even 100 watt bulb in them, anyone kept water thawed at -10F or -20F range? I have a nipple waterer with a bucket de-icer that freezes up when the temperature drops below zeroF so I'm looking for a solution. Thanks!