I monitor and control the pH in my calcium reactor, control the MH and VHO lights as well as alarm and shut them off if case of overheating, control the moonlights on a Lunar Cycle, control my heater and fans for heating and cooling based on tank temperature, control the return pump and have both it, the closed loop pump and powerheads on standby mode so I can shut them off for spot feeding, control powerheads on a wavemaker function, and other things I can't even remember right now. I also plan to use the switched contacts to turn a light on under the stand when I open the cabinet doors but those could also be used with their auto topoff system which I already have so didn't need.