Do a search on either one or both and I bet you'll find some stories of people nearly getting electrocuted. GFCI is probably the bigger (human) life saver. Ground probe will help alleviate stray voltages in the tank.
GFI is used to protect you (a electrical path to the mother Earth) from being toasted when one of your trusty electical equipment leaks.
It could happen in many ways. i.e. rocks fall and cut wires, pump seal leaks. Do youself a favour, get it 8)
I asked a electrician to install a GFI wall socket near my tank. The GFI hardware cost $5.
As for the ground probe, I think it is important as well. As most of our electical device is 2-plong (i.e. no ground wire), the grounding probe may guide electric leaks to ground and help trigger the GFI as it happens.
Doing some maint on my tank the other day- went to plug my rio ph pump back in, *(&^$%*&$%$# thing shocked me. I have both GFCI and ground probe. While I got a few seconds of "what the *&%@# is that?!?" the fish were totally cool. Ground fault popped shortly thereafter.
Rule of thumb- GFCI good for you, ground probe good for fish, rios good for waking you up... 8O 8O 8O
Also, GFCI hardware is cheap, while getting shocked sucks. Another thing to bear in mind.
To emphasize this point, a GFCI is a possibly lifesaving piece of equipment that every hobbyist should use for all tank-related devices. It comes into play when something fails and exposes an loaded electrical circuit to the water.
A grounding probe is merely something to bleed off weak, stray electrical charge that arises in normal operation of pumps etc.
Without a GFI circuit between your breaker and your UPS...it means once you get electrical shock and even if someone shut off the breaker, you still keep getting shocked. Ouch!
Stay on top of the gfci outlet too. They have a habit of going bad after a year or two. They are easy to wire, no need tor an electrician. For more reliable protection you can get gfci breakers that go into your breaker box. They are going to run you $30-40 but do not fail as often as gfci outlets. It is worth $30 to me to avoid even one shock, let alone getting electrocuted! You can install them yourself too.
another alternative:
you can purchase a short (3 or 4 foot) cord with built in gfci protection from some local hardware stores or grainger.
these are required on a lot of construction sites. Gfci's should be tested regularly, and should be tested at least yearly with a professional quality tester (not the cheap 6 or 8 dollar pushbutton kind) as it is quite common for them to go bad. 8O
I would find out if that GFCI in the link is one that has magnetic contacts. I say this because if it is and your power goes out you will have to reset the GFCI before power will be returned to your tank. Breaker and outlet mounted GFCI's don't have this problem.
thanks for the link googy, thats exactly what i needed! I also need a GFCI type extension cord comming from my ups so that it will trip the UPS. I heard someone mention one of these, anyone have a link?
Making your own extension cord with a GFCI is probably better and no doubt cheaper to do. That's if your comfortable making it. It's not hard to do at all though
As for plans being on the net? I haven't checked but i think I may be able to help you out with it. I'll try to draw something up for you with a material list. Everything you could get from Home Depot.