I noticed that a felt a tingle in a small cut on my finger when moving some corals around today. First thing I thought of is stray voltage in the tank. I grabbed a volt meter, stuck the black probe into the ground hole in the power socket and the red probe into the sump. I see the voltage flicker between 0.5-1V, but then I stick my hand on the sump or my finger in the water and it jumps to ~10V. Thoughts? Seems it has something to do with me grounding something or my body jacking with the impedance of the meter or something.

Anybody have a meter that they can test this out on their tank? Measure without touching the water or anything salty, then put your hand in the water and see if the voltage reading changes.