This is my first year raising chickens for egg production. i have 36 chickens and the weather here in illinois is not going so well. we have gotten down to 3 degrees. i use a 5 gallon plastic water heater. i used to use a metal one but it was a piece of junk because it would always leak. i need a water heater. i was wondering if i could use a water heater that says for metal water containers or if i have to use one that says "safe for plastic heaters." some say for metal heaters only. is this true or can i really use these heaters. also does anyone know if a large heated dog bowl work if i put that under my plastic water container. this might be a cheaper alternative for me. any comments?