OK I got my 2 150w MH's for my 75g. I have the lights 8" above the tank. The light penetration seems minimal. Would it be alright if I dropped these down a couple of inches, to say 6"? Also regarding the shimmering effect that the MH's give off, Is it possible to get too much shadow thus reducing the light consumption? Everything looks good in my tank. Since I am only running the 10K's w/o actinics for now, the coloration has a yellowish tone. I can tell that my acro's and clams look healthier than under the PC's but the tank isn't as bright. I'll be recieving my 20K's within the week so I will hold off on the actinics for now.