Rob,
Right now I've just got a 13W PC light fixture on the Fuge area. I should upgrade it to at least a 32W for the mangroves to really do well.
The mangroves are "red mangroves", which can exist in salt water. I've got long feather caulerpa for the macro algae in the fuge. I'd like to get some grape caulpera too. I ended up putting a bit more live rock in the Fuge than I was originally intending, but I couldn't resist the one big piece since its covered in little white feather dusters, which should contribute some to more water quality, provided I don't let them get completly over run with the caulpera. I also have a piece of live rock from the old tank with a nice growth of kelp on it. Stuff was growing like crazy until I pruned it back some. It just sprouted outta the rock one day, then grew about a foot in less than 2 weeks.
I am running a skimmer, a CPR Back Pack 2R, which came off my 30 gallon. The skimmer is on the 40 display, up near the overflow. One thing I have noticed is that I'm not collecting no where near as much gunk outta the tank as I was on the 30 gallon. I ended up transfering all the live rock (37lbs or so), and the live sand from the established 30 gallon into this setup. I ended up adding a new bottom layer of argonite sand to the Fuge, with live sand on top. Mostly all older live sand went in the display. Added some more live rock too, about 5 lbs. I'm lucky because I have a very good LFS right down the road who let me pick out some good cured pieces from the display tanks in the shop.
I spend almost as much time checking out the fuge area as I do the main display. Part of this is also because I upgraded my lighting on the display to a 250W 10K MH along with 2 96W actinic VHOs. I'm only running the MH's about 3 hours per day right now so I don't stress out or burn any of my corals that I transfered. (That was a great tip I read numerous times on this board).
The MAG-7 pump is great so far. I didn't have room for an external pump in the stand under the 40. I'm on the 3rd floor, so as much as I would like a bigger tank (like the 90 your working on), I'm a bit paranoid about it going through the floor. I havn't noticed any extra heat from the pump, tank temp is right at 77 degrees. I was glad to get the heater into the sump area, right where the water enteres the sump. I can use that area to run carbon every once in awhile too, something I couldn't do on the 30. So far I'm very happy with the setup. Could not have done it without this board though.
Heres a picture of the display tank