Wattage is not important! What is important is that you have the right width of heat tape for the size of tubs you have!
Thats only partially true. I use 3 or 4 inch for all my tubs no matter what size.
Room ambient temps play a roll in the size you need. If room is a steady 78-82 you only need 3-4" flexwatt. If room is cooler than you may need larger sizes like the 11" to help maintain a warmer cool side.
Wattage plays the part of how hot the tape can get. I like covering roughly 30% of the floor with heat tape of whatever container im using. So 12qt gets 4" and 28qt and 41qt get 11". Maybe its too much but my babies eat and my adult male eats and there all very comfy in there tubs this way. This is how i do it though. Theres many different ways to use flexwatt and none of which seem wrong if all applied in the same fashion.
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