I would talk to them, but I just got 2 Compact Atlantik v3+ fixtures for my 24" deep 120. It says on their website you can get different optics for tanks over 24" deep, but I'm not sure that the Atlantik fixtures can handle 48" or not. I will say these lights are very powerful, and if you crank them up you might be okay. You may have to go with some of their pendant fixtures or something. I would contact them directly for advice.