You can use a dimmer, but if you have big temperature swings in your room, you're going to have to adjust it. It puts out...say...50% power regardless if what the room temperature is (assuming you have it set to 50%...). I would still use a thermometer in conjunction with it. A thermostat really is the best way to go...but I've used them successfully in the past. Hydrofarm (http://www.amazon.com/Hydrofarm-MTPR.../dp/B000NZZG3S) makes a relatively inexpensive one that works well. I've also used one from ZooMed (http://www.amazon.com/Zoo-Med-HygroT.../dp/B0019IHK9Q) with success.