48" light on 6 foot tank? Is light disspertion effected by bracings?

[JLAudio]

I have a 125 and would like to A) save on wattage by only having 2 MH lights and B) see a few on sale. My ony concern is how the bracings will efect how the light hits the tank, but Im thinking if I keep it some 10" off tank it might be ok. Anyone else just use the 2 lamps for a 125 or another 6 foot tank?