We had the same issue a while back. Grab a volt meter, ground the black and dip the red in the tank. Once you see if there is 'tricity in your reef, you can unplug things to figure out what failed. Our reef is in the garage and after this happened to us, we started a "no barefoot reefing" rule. If your hand touches water you must be wearing shoes and not standing barefoot on the cement floor.
Cheers! Mark