First some background. My experiences with frozen founts go back to when I was in high school, and I worked for dog kennel that kept all kinds of birds for dog training purposes. Every night when we were expecting sub-freezing temps I'd have to go out and pull all the founts, empty them, and then stack them in the office. In the morning I'd have to reverse that. Always seemed like a HUGE pain in the butt. So fast forward about 10 years ago when we started keeping chickens I built this With a 100 watt light bulb inside this worked pretty well as a heated base. But there were a couple problems. First and most importantly there was no thermostatic control, so it was on and burning 100 watts 24/7. Second it turned out that the area underneath the base made for some apparently awesome mouse housing. So in an attempt to resolve these short comings I installed a heat lamp directly over my water, and regulated it with a thermostat mounted to the wall. Worked pretty well, but there's still some problems. First of all heating the water indirectly with a heat lamp is inefficient to say the least, secondly in order to trigger the thermostat off the entire coop has to come up over the thermostats set point. In other words I was heating the whole coop in an attempt to keep the water liquid. I stumbled on a website where a guy was using one of these glued to the bottom of a pan with high temperature ATV sealant: http://www.oreillyauto.com/site/c/detail/FIV0/24100.oap?keyword=oil+pan+heater Now we're on to something. Directly heating the water via the bottom of the fount worked VERY VERY well. Too well actually. I was watching most of my water in the fount evaporate off in less than a week so obviously I'm closer but what I really need is some sort of thermostat that has a submersible remote probe with a fairly low temperature range. I dug, and dug, and dug through the internet looking for a solution in amongst the folks that keep reptiles (shudder), and the folks the keep aquariums. I finally found this: http://www.amazon.com/Hydor-HYDROSET-Electronic-Thermostat-Temp/dp/B0006JLPEA Ohhhh yeah, as they say this is the bee's knees. Friday night/Saturday morning we got down to about -15f outside, interior coop temps were about 8 degrees all night long, and the water in my fount was still a liquid. I've been watching the water temps pretty closely all weekend long and they've been hovering right around 70 degrees with this thermostat set at it's absolute lowest setting. If I could set it lower say down to as low as about 40f I'd be even happier, but right now I can't complain about an additional 30 degrees of water temp. Still beats everything else I've tried.