The most common issues for not being able to keep xenias? Too much light, not enough light. too much flow, not enough flow. Over skimming, under skimming. Inconsistant water params, consistant water params. My point is, I have read and experienced all of these when keeping and killing xenias. My first reef tank was a 20g long with a sea clone hob skimmer and 2 pc lights. Several different xenias took over the whole tank. I would rip them out by the handfuls and give them away or flush them. Upgraded my tank to a 45g tall with mh lighting, new skimmer and sump. Acclimated xenias to new lighting by first putting them in the tank floating upsidedown, them palcing them at the bottom of the tank with the lights on for gradually longer periods of time. Water params remained consistant with the first tank, and I added nothing different. None of the animals survived.