John he has a space in the sump he is making that he wants to do a refugium in.. although the coil could be cool.
crutkas, why not caulerpa? It's more of a sponge than Mangroves..
Most of what I know on this stuff I put here, fyi:
http://www.3reef.com/refugiums.shtml
There's also posts at the bottom of that page by other people sharing their experiences...