MandarinFish,
I have mine in a 60"l x 18"w x 28"h 120-gallon tank. There are only two fish in it(achilles tang and a flasher wrasse), and there is a lot of open rock work. If you want to see an old thread on RC about my tank, here's a link:
http://www.reefcentral.com/vbulletin/sh ... of+my+tank