Quote Originally Posted by snakesRkewl View Post
I use both 3 inch and 11x12 inch

3 or 4 inch is too small for large tubs IMO
The idea is to have them radiate heat outward to give you a 7-8 inch x the length of the flexwatt, heated patch. If you're using a 41 qt tub, that may be a little small, but very useable.

Jim Smith