Thanks for the comments everyone.
Grrrit, not sure if you saw but I decided not to use the green painters tape, and went with green acrylic paint instead. Much easier to apply on the lights and it looks great!
I have finally come to realize that I am not going to be able to use the metal halide setup with the display tank. I've looked for hours, days, and weeks trying to find out what model it is or even what company made it, but no one has a clue. Even major reef lighting companies are stumped. They called it an "anachronism of a light fixture". Therefore I am unable to find a stand for it, or any screws, latches, holders, hardware, or any other device to suspend it from the ceiling or otherwise. Big disappointment, so I'm just going to use it on a rack in my frog room and search for new light fixtures for the display tank.