I had xenia growing in one of my tanks when it was newly cycled. I used the xenia from one of my other tanks. It grew and spread in the tank for about three months and then it appeared that all the xenia died. A month later, xenia appeared all over the tank and to this day I have to remove some because it interferes with the growth of other corals. The tank has been running for almost three years. I don’t know what caused the die off, but if your xenia dies off it will probably come back if your other corals are doing fine and growing. I find this coral to be very easy to care for.
The only thing I did different was my nitrates were around 20, and Ive got them down to 10 now. I also added some carbon in the filter. Other then that everything is the same. Other corals seem fine, the xenia has been like that for over a week now.