Originally Posted by banditpowdercoat (Post 717358)

Stray voltage can be introduced my leaking through the wire's insulation, or by Induction. Ballast have a huge magnetic field. And properties in your tank, can react and make electricity by a induced magnetic field into the metals in your tank.

I've been shocked off metal structures that were beside Flourescent lights before. The Ballast was inducing about 90v into the metal. Not much current, enough to just feel a little tingle, but it was there. Ground probes are good.
That's also a reason we ground copper water pipes in your house. Electricity running in wires beside the pipes, can induce voltages into the pipes.