Oh and also just thought that you don't seem to have any current or amperage behind the stray voltage meanign that it may be coming from an alternate source. If you had any type of line amperage or current behind the voltage I'd assume it would have the oomph to push it into the main tank. It seems to have no amperage and is fizzling out in the sump.

And yes I'd assume a good ground would help divert it. And would be recommended.