ok so I set my tank up 3 weeks ago. Since it’s still very warm in Florida, I haven’t used the heater. The thermometer the tank came with always read 82 degrees. I bought a digital thermometer and have it on the opposite side of the 55 gallon tank. Heater is a Top Fin 200 watt the tank maintains 80 degrees during the day, at night it is 78 when I wake up. So I plugged in the heater and set it for 80 degrees. It comes on and off, the temperature climbs to 81.4! I back the knob down to 78 degrees, but the heater still comes on and off. I’ve now backed it down to 75 and the tank temp went down to 81. Is it normal to have to keep the temp setting on the heater lower than you actually want?