I go with the 2-3 watt per gallon group.
Every winter the failed heater posts start showing up.
Boil outs, huge wattage heaters sticking on and making fish stew.
From what I have read, fish can handle cold water a whole bunch better than too hot.
I have a 100 watt for my 55. Stayed on for most of 24hrs, before tank got to 76-78.
Fine by me.
Sure, look where you live..Florida..So?
I live in a house.
I guess if you were living in a cardboard box, in back of a Sears in Butte the 2-3 watts per gallon wouldn`t work too well.
Guess what I am saying is, use the least amount of watts to maintain a steady temperature.