I understand that I can have a heater with more wattage tham I'll actually need; after all that's what calibration is all about. Ideally the heater shouldn't be running all the time.
I guess my concern about sizing wattage to the size of tank comes from things I've read over the years about heaters getting "stuck" in the on position and cooking the fish. I've never had it happen or heard of it happening, but it's one of those things that's always mentioned in magazines and books. (The aquarium version of an "urban legend", perhaps?
) I keep in eye on the heater in my freshwater tank and always heave a sigh of relief when our brief winter is over so I can take it out.
I love that I'm getting so many different answers to this question. When I asked it I had no options. Now, I've got choices.
Thanks, everyone!