I have 5 gal buckets with nipples in bottom and i'm thinking about using fish tank heater to keep the water from freesing what do you think? http://www.ebay.com/itm/3-25-Watt-A...849?pt=LH_DefaultDomain_0&hash=item45fd645e71
The only thing I do not like about the aquarium heater is the minimum temp is about 60. Or at least that is what I have been able to find out. We, like you, have very cold temps and water at 60 degrees will evaporate quite a bit. We chose a bird bath de-icer, but they are about 30 bucks each. Just a personal preference really. Looks like a screaming deal and the great part is you will have back up!! Not sure why you would have to change out the water every other day.
I've used an aquarium heater successfully for the last 4 years. Our nights are usually below freezing in the winter, sometimes below 0. Our coop doe shave a nice southern exposure so it gets warmer inside during the day. So I have my heater connected to a thermocube (available at hardware stores and feed stores (~$12?) which turns on the heater when the air temp is below 35 degrees and turns the heater off when the air temp is 45 degrees. So it saves a bit of energy that way and doesn't make the water too warm. The water has always been fine every morning using this method. The only caution with aquarium heaters is that many of them have to be totally submerged at all times in the water or they will shatter. So read the instructions carefully on yours. If it needs to be submerged be surge that you have enough slack in the cord to have the heater on the bottom of the bucket and that you fill it every day.
