I have to heat during the winter as my lower floor gets pretty cold. I do what Bobby said using a plastic storage bin from Home Depot. Sometimes I use a small pump to circulate the water and sometimes I just toss some bleach in the water. If I don't do one of these steps, the water starts to smell pretty quickly. I have a nice temperature controller left over from my reef aquarium days that I use to control the temp precisely. You can build one pretty cheap from eBay if you want. It will make precise temperature control very easy.