I've seen those grounding probes and always wondered who buys them and why. I don't know of any FW
people who have one. Maybe they're meant more for saltwater folks since SW
conducts electricity better than fresh. Or maybe they're needed if you keep fish that navigate or find food using electrical fields.
Like Jaybird said, those grounding probes are meant to dissipate low amperage static charges. GFI outlets are the best way to protect you and your fish from getting zapped by high amperage current leaking from faulty equipment.