An on/off one would shorten the life of the bulb greatly. Just an old school, get at home depot light dimmer. It allows you to dial the proper temps in with a heat gun. Works great if you are in control of your homes thermostat. It also allows you to use a higher wattage bulb, and turn it down to greatly extend the life of the bulb. Most breeders control the room temperature or large collection keepers usually have a room where they can control ambient temps overall. In your case I think this could help, Peace.