I use the thick rubber fish tank heaters....like this one:
http://www.amazon.com/Zoo-Med-Betta...8&qid=1410965757&sr=1-4&keywords=betta+heater
They are super cheap and low watts....so that means less energy cost. It got down to 18 below zero and kept a hole of water in my glass water dish. Above zero it kept the whole dish liquid.
http://www.amazon.com/Zoo-Med-Betta...8&qid=1410965757&sr=1-4&keywords=betta+heater
They are super cheap and low watts....so that means less energy cost. It got down to 18 below zero and kept a hole of water in my glass water dish. Above zero it kept the whole dish liquid.