Looking for wet/dry

I guess my first question would be what do you want the wet-dry for? I seldom encourage their use in a SW tank, simply because the bio-balls/media can trap solid wastes where cleaners can't get to them, so they rot and contribute to high nitrates unless maintained vigilantly--either a pre-filter that catches the solids and is cleaned frequently, or by rinsing the solids free of the media directly.

If you want someplace to hide equipment and increase volume I would suggest adding a sump instead of a wet/dry. Sumps are easy to build--just need a large tub, and some plumbing.

Check the DIY pages here, or search on DIY Sump--lots of hits. Think Garf's has a page on them too....If you don't want to add a fuge (and the lighting for one), you pretty much just need a tub/tank of some sort, some baffles (egg crate works well), and the pump/plumbing. If your tank isn't drilled, then you'll need overflow boxes too. Here are some links: http://saltaquarium.about.com/cs/sumpprojectsdiy/