i have found pom pom xenias need acceptable stable ca/alk levels for long term success. most will thrive in under par water for a week or 2.
also, flow intensity n pattern will affect its pulsing.
SO you're saying if I change my water with Reef Crystals that it's not enough. I have two Xenias - two kinds that is and both have thin stalks and long tentacles - I beleive they are this way because of two things. Not enough light and too strong a current. I am going to add more light and see how they go from there. These are supposed to be easy to keep. I agree with the original poster - right away people want to treat you lkke you dont know what they are doing. I can tell you that many a hobbyist have had ZERO success with Xenia - there is some kind of magic involved in placing them - I think that's what is the key. Placement!