you shouldn't have to shut off your heater. If it's set for 80 and the tank is over that, it won't be adding any heat to the tank. you should aim for a stable temperature, so if the fan everyone is recommending gets you down to 82 in the day, then set your heater for 81 or so, so you won't get much fluctuation at night. you don't want to go from 78 to 82 and back every day.
54g all-glass bowfront corner planted FW
Red tiger lilly, Rotala Indica, Sagittaria Subulata, Micro Sword, Cardinal Plant
Fluorite Black sand and gravel