Nano reefs are a great thing. They have made keeping reef aquariums accessible to almost everyone, no matter what their income. However, with such a small volume of water, equipment failures can be catastrophic.
Even the best aquarium heaters are prone to sticking on or off. In a nano reef, it doesn’t take long for a heater stuck on to wipe out the entire tank. A temperature controller works by cutting the power to your heater when your tank temperature exceeds your set point. More advanced aquarium controllers can sound alarms, email you, and shut down your lights to prevent over-heating.
The most inexpensive aquarium controller is the ReefKeeper Lite, which we sell for $125. This is a video demonstration on how to quickly and easily setup the ReefKeeper as a temperature controller.