I was considering an 80 watt or 120 watt to start with, but my main issue was I'm unsure if 80 would be enough and was contemplating going for a 120 to be safe...I'm unsure if that would be overkill, however. I don't mind how much of the cage it takes up, since it's on the roof and super thin, but understandably I'd rather not pay for a 120 if an 80 would be enough. I'll gladly buy it if it's the best option for my situation, though. c: