Hey Breutus,
What are the red corals in your pics. They are really nice looking.
Sorry about your tank problems... As far as the GFI goes (skipped over most the the discussion so I hope I'm not repeating), the GFI will trip if there is more than a 5 milli amp imbalance between the hot and the neutral.
With out a grounding probe, you might have tripped the GFI since some of the current could have found it's way to ground. With a grounding probe you would have most likely tripped the GFI since more of the current would have found it's way to ground.
I personally have everything on a few GFIs. And have grounding probes. Good luck.