hey James, I didnt want the center brace in the middle because I like how all the doors are side by side the whole way across, and it also makes it easier to work under the stand. Originally I was going to use a 75 gal for the sump but I ended up having to use a 50 due to the height on the 75 and not being able to get the lid off my skimmer easily.
I used a 2x8 for the top span and I am not getting any deflection. I put braces on the back mainly just because I had extra wood and I would have a place to mount some stuff just in case.
Some of the corals in my tank have been with me since I had my 29gal in 2007. Everything was moved over from my 72 so some stuff is pretty large.
here is a pic of the purple cap I gotfrom reefwatcher taken on 1-7-08
and I took this picture of it when I broke my 72gal down and moved it to my 180 on 1-29-10
I know for sure it has grown since then under these mh too.
You can also see my hammer frag and frogspawn in that pic now that i look at it haha