You're describing a "
aquagiant" reef-ready tank to a "t".
I have one of those, and so do a few others here. They are good, but can be a bit of an issue to get some plumbing done. The glass ledges inside the overflow come out pretty easily, and I've taken them all out of mine, and put in a durso standpipe. That makes the overflow work a lot better, in my opinion.
Matt