Alright, well there is one aspect to this system that I've been pondering for the last couple of days. If you'll remember, the tank is a standard 30 gal (36x12x17) and I planned on using 100% natural light via an east facing dining room window. This provides some pretty intense light in the morning and indirect light throughout the afternoon and evening. Plenty for mangroves, but tank inhabitants will have to be very carefully chosen. Although the light withing the tank is near blinding during the morning hours, I'm not sure if it provides enough light throughout the rest of the day for corals, etc. Just a couple inches of Pure Aragonite, a powerhead or two for circulation. The tank would be open top with the water level a few inches below the top. Minimal LR, hopefully hefty seeding from other tanks and established SB's (hope to get microfauna crawling all over the place, as well as sponges, etc.) This tank could be pretty nutrient rich, so I'll obviously have to use that as a benefit in choosing inhabitants.
Now, to the primary question. One of my main goals is to have the trademark roots on the mangroves. However, in our previous correspondence, you mentioned that the roots could easily bust the seems of a tank (and having experience pulling lilies out of a gravel laden pond bottom, I know their strength). So, the viable option would be to keep them in pots to prevent this. I would collect muck from some eelgrass beds over in Puget Sound to put them in, since I assume this would contain a nice amount of nutrient for them. Now with the mangroves planted in potes, would it still be possible to encourage some of the proproots above the water without getting into trouble, as long as many of them are still contained within the pot?