Maybe this is a dumb question, and maybe there are other types of gear that could be used but. . . my aquarium is in a room that can be drafty. . . and there is always the possibility that the door to the room will get left open (door to outside). . . could you run your main heater at like 78 and then have a back up heater set to like 75, just in case temps in the room drop below what your regular heater could handle???