Radio Shack sells a timer that works by sending signals through the house wiring to turn on or off "modules" that plug into wall sockets and have sockets themselves. You set an on itme and an off time, plug the module into the wall, and plug your tank lights into the module. The signals turn the module on and off at the set times. It is accurate to the nearest minute. The only noise is a clunk! when the signal makes the module connect or disconnect. The timer can operate up to 12 different modules, and each module can have one or two on and off times set.