I have a 45 tall with center brace. its 36 long. I moved the mh from the center and put it on the left side. So my light loving corals are on the left and center, while the shrooms and others that need less are on the right. It looks totally awesome as sun penetrates the left as a direct hit, the middle as a lit area and the right more blue with rays passing thru it. I have 1 4" fan that does 90cfm and I wrapped the center brace with metal reflective tape, same as used in hvac insulation wrapping, available at home depot. The air inside the canopy get to 95 and the bulb itself goes up to 150, not enough to melt the plastic. I run the mh 7.5 hours a day and its 5" off the center brace