Having ANYTHING plugged in will cause the voltage to go up, even an incremental amount. I found a few good articles on that here:
http://www.reefs.org/library/aquariu...996/996_5.html
however - the biggest factor is that the ONLY time I feel it is when I stand on the "wet spot" on the floor. I move off of that, and nothing.
I had the + wire of the voltmeter in the tank, I took the ground and stood on the spot, the needle moved to a VERY small amount, but it moved. I took my foot off that spot, and all was hunky dory.
How does this make sense?