Are you sure that's a 40 gal? Sounds like a 55 to me. I have a 40 and it is 36". I'm not familiar with a 48" 40 gal.
At any rate, if you are planning a reef tank, i.e., corals etc., 96 watts of PC is NOT enough. It might make a nice dawn/dusk addition. But not enough to support the life and well being of true reef animals, and have them thrive.
My humble .02
HTH
Hermit