Im lookin for a heater on a tank thats in a room that kinda fluctuates temp wise. so i need a heater that'll shut off of course whenever its at 83ish n always turn on if its cold. if the temp drops even lower then the heater works til the temp is back at 83ish... i've seen digital heaters that have a digital display where you set it at 83 degrees and it does its thing to keep it at 83*. the tank is in my garage n it gets kinda cold at night but during the day it isn't as bad. any recommendations on a heater to use? the tank is 400gallons. thanks