6 T5s with individual reflectors should fit into a canopy, unless there's something somewhat unusual about your canopy. 5 T5s with individual reflectors fit into our canopy with plenty of room to spare for a 6th bulb if I wanted to add it.
Ok... I'm new to it so I really don't know exactly how it works... I guess I have the average canopy, but I was looking at the space I had up top before it hinges and I just didn't think it would fit but u guys know better than me... I found a great deal on a nova extreme pro T5 fixture 6x54w for $345.
I have a 125 that the distance from the front hinge to the back brace of th canopy is about 18" I believe and I have a Nova Extreme T5 8x54 screwed underneath