I would suspect if the halides are a retro or the VHO's that somewhere you have some salt creep carrying current into the aquarium. This tends to be an issue with retrofit type fixtures. Thoroughly clean the entire assembly and check for any loose connections. Also, verify the sockets with an outlet checker as I discussed- you may be amazed to find out more about the wiring in your house, I know I was and I redid several cicuits after getting one of those. Then try the pump with no lights on the tank and see how that works but please be very careful- what just barely tickles with shoes on could kill you on a wet floor, it takes only 1/10th of an amp to kill someone and I would consider consulting an electrician.