10Gallon
Aquarium Advice Regular
I've noticed when using a heater without a thermostat controller, the temp fluctuates more. In my 10G, with the Aqueon 50 watt, the temp would go up and down about 3-3.5 deg every couple of hours. Other heaters I've used were like that maybe not quite as bad, though. I got a Finnex analog controller and with that heater the tank stays within a degree. Why does this happen?