Depends on where the tanks are, the ones in the basement were around 60 - 70 F depending on the temperature and the ones in my bedroom were between 65 and 80. It just depended on how cold it was outside and if the door was closed or not.
oh ok I might get a heater..When the time is right. I hate losing fish to somthing that could've been avoided, but Mostly when I can I will not use a heater.