Halide Lighting Ballast problems!! help!

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Thanks reefgeek. I didn't actually realize there are two ballasts (my ballast box has just one plugin), that would explain why one could be working. Unfortunately I don't know what kind of ballast it is, bought it all used from another reefer here, so I'll have to try to see if he knows. I guess it is OK to run just one side then for now.

I'll try the other side on its own later to see what happens. I assume something is shorted out in that ballast and that is why its tripping the GFCI. I'll open it up later and have a look, but for now, I need to leave it on tonight for the corals since I wasn't able to turn it on till 5PM. Thanks for the help.

Love to hear any other suggestions or if someone knows where I can get replacements ballasts (in Calgary perhaps??).
Tank dimensions are 4'x2'x2'. Its only about half full of water right now, as I'm slowing increasing it from my 33G I upgraded from.