Tank looks good...even with fake corals, and I don't usually like them. lol
I also wanted to comment on your fish selection. Please don't add a tang (of any sort) to a 4 foot tank. I assume your 120 is a standard 120...which is only 4 feet. But ESPECIALLY don't add the Naso. Gorgeous fish yes, but your tank is very undersized for him. We are talking about a fish that is in the Unicorn Tang family which = lots o' size. Even as a juvenile the tank is too small, he needs tons of swimming area. A fish that gets upwards of a foot and a half needs at LEAST a 6 foot tank (and in my opinion even that is too small for this fish).
I know you don't have to take my advice/suggestions but at least see what others think. And I am not trying to make fun or criticize, I just want you to be aware that the fish is not right for you at this time. Again, the draw to obtain this fish is great because most LFS have them as little guys and they are very attractive...but please pass on this fish!
Pete
P.S. Just because 'lots of other people' have tangs and even Nasos in 4 foot tanks, doesn't make it right!