interesting aquascape... I see potential for some cool coral formations... I'll be following along on this epic reef journey.
As for the Xenia... it is a very finicky coral. I have had perfectly healthy colonies of Xenia melt and wither away for no apparent reason just to have it grow back a few months later... It also can depend on the species of Xenia. I've noticed that some of the tan species that have longer stalks are less-hardy than their white "pom-pom" counterparts. Maybe try moving it up higher in your tank to give that little bit of extra light.
As far as corals go... I would stick with some of the easier to care for and more colorful zoos and mushrooms. Ricordea make cool mushroom additions to a nano-reef. As far as LPS is concerned, I would stay away from anything that can develop long
sweeper tentacles... ie Galaxy, Frogspawn... try a Torch or possible a
hammer coral... an open brain would fare just fine as well.
Good Luck.
