You don't have to hang them that high, If it's right on the tank, then you won't need to do anything, if it's a few inches above, you might want to build a reflector shroud kind of like I did to shunt the stray light downward. Hilde is right tho, they are wide angle (120 I think).
I wired it up it. It seems that my one cfl puts off more light I think I'm gonna need two of these lights per a tank
Tapatalk is not allowing me to post a pics but I don't even think this one light will be enough to grow anything