Heat will still be an issue with the 34g. I run 2x 30g's lit by 150w DE mH on each, as well as 2x 54w PC (or 2x 24" T5 on the other). I use a ton of fans (including an inline fan the polls all the air from the room and dumps it into the attic), open tops as well as the room is the coolest in the house normally due to position and construction of the house.