Sounds great. If it's used to a 'water substrate' then just keep it that way and keep your water quality within normal ranges in the temp tank - shouldn't have to worry too much, but again, you don't want your Alk to sky-rocket, Ca to crash and/or have huge pH Swings or something like that - make sure that your Salinity, temp, pH, Ca/Alk,etc. are all basicaly stable. Maybe change 10-20% of the water every week or 10 days to keep things happy... Stable and gradule is the name of the game
And once you get your setup going again - do consider putting those roots in some sand. Growth will be greatly accelerated IME.
I start my propagules floating. I tend to get the cheapo propagules with no roots/leaves and poke them through a 3"x3" styrofoam sheet, let them float until they start dropping long roots (not the short fuzzy ones), then I fill a mason jar/acrylic box with sand from the DSB (~2" as if it were a DSB) and set the plants roots on this. It of course is raised high enough to keep the top of the propogule out of the water. This seems to really spur on the root production as the seed "thinks" it's found a place to grow. Likewise, once it has a healthy root ball, and a percieved location to live, it'll start popping out leaves. The secret to a nice root ball is to gently pull the plant back up out of the sand every day or so to keep it from making any headway into this temp DSB. Once the roots are really growing, the hard top will come loose and the leaves will begin to grow out. My propagules sitting on the sand jar usually tip over a couple of times and float around the tank on their side, this has never seemed to hurt anything.
I figured out the "roots in sand' accidentally while floating my propagules. It seemed that they would stall out as they were growing roots. One of my floaters 'landed' on a chunk of LR and within a few weeks it had made noticable headway over the other Propagules in root production. ...Now, they all get the sand treatment.
Once the roots are long enough to keep the propagule tip out of the water, I use Egg-grate wedged between front and back glass at water level with the propagule through one of the holes and the roots resting on the tanks DSB. When the Mangrove is stable enough to stand on it's own, I remove/cut away the egg grate and away it goes. It'll go through phases of leaf production and then root production. If you are after a healthy exposed root structure as I was (for my eel to play in) I found that by pointing a powerhead at the trunk of the Mangrove causing a gentle wiggle/movement in the plant body will usually make the plant drop a banyon (root from the side of the trunk) down into the DSB to stabilize itself. Once the root is in the DSB, it's time to move the Powerhead
Also, when it comes to pruning. Don't be afraid. Keep that puppy trimmed back as they will usually send out a healthy quantity of new buds. More if you trim them. I let mine grow straight up to the overall height I wanted (about 17"), then trimmed it back about 7". It's important to keep at least a couple of healthy leaves on any given branch that you wish to keep and to trim it near, but not at any leaf/branch you with to keep (since it'll usually die back to the last available 'node' on the stem). At each 'node' closest to the point you cut, the plant will usually send out at least 2 more buds (along with other locations around the plant as normal growth). These two will shoot out as a branch with sets of leaves. I usually let them go to the edge of the shape I'm looking for and then cut them back to just above the first set of leaves, the process repeats with the plant sending out another set of branches from near this cut...
From this I ended up with a 18" tall plant that has a nice large (growing in girth) trunk and a semi round 9" head of leaves/branches. I've given away several of these puppies as they grow to others who want to get started with Mangroves. At this point I have one nice mature Mangrove and one that is in the process of shooting out leaves. The propagule mate to this one (got a pair as the last time) died. I'm not sure if this was just a statistcial death - or if it might have done better if it was dropping roots into sand.
IME, unrooted/unleafed propagules have a 50% success rate. I'll probably give up on the cheapo's and start buying mine with leaves and roots already - it saves you a good 3 months anyway.
But then again... I'm anal about my plants - this comes from training Bonsai for a few years before I got into Reefing.
Hopefully we can get some Mangrove Experts in here to post some of their info too. I hope we get some other people's experiances as well.
Best of luck
John.