Hi all. New here.
A couple of thoughts:
Yes, looks like the grounding probe functioned to electrocute your livestock somewhat. You probably didn't have it plugged into a GFCI outlet, which would have blown power to the whole system, which in this case would have been the better outcome. If you don't have a hardwired GFCI outlet near your tank and don't want to install one, you can buy a self-contained type that itself plugs into a regular outlet.
On the advice of an engineer, I added a 1000 ohm 25W resistor to the cord of my grounding probe. Now, small voltage leaks won't result in any current, harm anything, or trip the GFCI, but they will might still shock me next time I put my hand in the tank, which is ok, that'll tell me to look into it further. Any leaking voltage above 20V will still trip the GFCI. This way, less important leaks or transient events won't shut down everything.
Robert Iuliano: That would be a fantastic thing to have. As zondebok mentioned, all it would have to be is a simple switch of some kind, no there's no stray current, or yes there is. Hook it up to the Apex breakout box and many new possibilities exist; shut down specific items, email or text a warning, sound a siren alarm. I would buy a few of these.
youcallmenny: How do you actually do that? Just set it to a voltage range and dip one of the electrodes in the water? Is it that simple? If everything is functioning properly without voltage leak, should it read zero?