OK. I have the five gallon Galvanized Steel waterer for the girls. I see that it has a handle so that it can be hung. Is there a difference if I hang the waterer or set it on the floor? Will hanging it keep the water cleaner, longer? It's usually filthy five minutes after I clean and re-fill it. Also, it's going to get down to 37 degrees tonight. What is too cold for them and when will I need a heat source?