As fort said that stuff would really help out but xenia are one of those corals that can thrive one week and die off the next.. some people can't even keep it at all which no one knows exactly why. A little reading led
me to a lecture that touched on xenia and from their experience they got the best growth out of it when they had .02-.05 ppm
nitrates. So it seams to "clean" of a tank could be the cause to many people not getting the growth that its capable of.