Canopy's

[newreefy]

I am starting to build a canopy for my tank (48 x 12 x 24). I am planning on putting two 48" VHO's under it. What does the inside length have to be in-order two hold 48" bulbs since there is also the endcaps that go on? I dont want to end up with a canopy that is not long enough to fit 48" bulbs. Would i be smarter just to use 46.5" since my tanks is only 48"????