First are you sure it's pulsing xenia?
There is Cespitularia, Clavularia and Xenia that doesn't pulse.
And Pulsing Xenia is an excellent monitor for Alkalinity levels. When everything is dialed in nicely they pulse in a beautiful rhythmn. When Alk is off when they pulse the fronds won't come together all at once, the colony doesn't pulse to the same rhythm, or only half the heads will be pulsing.
And sometimes if Params are way off the pulsing will stop altogether.
Dave B