I finally brought my Extech meter home. Put it on AC volts, autoranging. Showed 0.07 volts unhooked to anything. Grounded the black probe to the wall outlet ground and touched the red lead to the water at several different places, sump, skimmer, frag tanks, etc. Got a constant reading of 34 volts AC. That surprises me a bit. No tingling from touching the water on a concrete floor with wet bare feet, so there must be almost zero current. I am wondering now if a ground probe wouldn't be a good idea to bleed off this small charge I am seeing.