I would. 23" is kinda deep. It does depend on what you want to keep though. Brains must rest on the substrate, so you'll need enough light penetration to reach them. In a tank that size, if you went the
MH route, I'd get 2 of them. Now I _think_ 250w bulbs would work for ya. If you wanted
SPS corals, or even clams, I'd consider 400w, but I'd definitely get more input. I'm a little green to the lighting arena myself, and I'd hate to lead you astray. My tank is about 20" deep, and after the
DSB, there's only about 15"-16" of water left to go through. I'll be using 3x250w
MH. One
MH bulbs covers about 2 square feet, so in your tank, I'd go with 2 or you'd end up with some dim areas. This is, of course, if you ever decide to upgrade, and whether or not you will need to, is whether or not you want high-light corals and/or clams. Hope this helps!