I use any heater. as long as it's in good shape.
I have old hang on tank heaters... I've never had a heater stick.. the only thing that goes on when I empty the tanks, sometimes I forget to unplug the heater.
Sounds like frying bacon when you refill the tank.
I use visitherms in my larger tanks, an ebo jager in the 110 and Tronics in the other big tanks. (the hang on heaters only really go on 10's, 15's and 20's)
Which reminds me I should really put heaters BACK IN/ON my tanks. they have been on hiatus for the summer. Now it's getting cold up here in Canada Eh? Some tanks are running around 71-72. Burr...