I have a 6x2 180 aquarium, running 3 MH lights, and 2 x96 watt CFs. Someone, somewhere, mentioned that the MH bulbs would provide more light if they were perpindicular to the tank front, as opposed to being installed parallel. If I install them perpindicular, I will have problems with interference with the hinge area, but I can probably work around it, if it were worth doing because of increased light efficiency. Comments?

I haven't heard that about MH lights, but I did read that the ones with the bulb itself sitting vertical was more efficient than with the bulb sitting parallel to the floor. I don't know if either bit of wisdom is correct.