Electric Current in Reef Tank!

I attempted a water change tonight. When I put my vacuum into the water of my sump (pump end) I jerked my hand back. When I touched the water, I could feel an electric charge, almost like a steady static electric power. I've heard about this before, but never experienced it. I am a bit lost, please help! I have unplugged everything in the sump, but still get a charge. I removed the collection cup of my skimmer to change it, and when I touched the skimmer that was charged a bit too.

A few facts, the display tank has the powerheads, and there is no charge there. The strongest charge is on the pump (return) end of the sump, but doesnt appear to transfer up to the main tank. I have unplugged and turned everything off. What do I do next!??!?!??!?