Retired Viking
Fish Connoisseur
Depends on how cold it gets in your house, I live where the winters get pretty cold. Having two also puts less strain on each heater. You could set it up where the temp is lower than the other one so it only turns on if the other one is not working. But it does add wires and more stuff in the tank. I have a UGF so I just put them next to my up lift tubes.