Xenia problem

Robsreef, check your salt level. I have noticed that if your salinity is higher than 1.028 they will slowly stop pulsing.

 

Sometimes my xenia closes up for a day. It comes back the next day. It May close for a number of reasons. Hermit crabs, snails, starfish, ect. can effect other corals as well. My blue linkia crawls over and around my bubble coral which makes it retract.
Anyway, if it doesn't come back after a day, you should start to worry.
On the hair algae problem, be careful of overfeeding and make sure you do regular water changes. Are you using RO water?

 

Im kinda having some problem with my new xenia too. I got it 4 days ago and it was still pulsing during the acclimatation (drip method for well over an hour). Now its not pulsing and its tentacles and stalk looks kinda deflated.
Ive read I should not worry unless it starts melting. What exactly do you mean with "melting". Im a spanish speaker and I picture ice and snow melting. But i just cant imagine my xenia melting =S

 

dont worry if it melts you will know.
imagine puttind a sugar cube in water

 

Check your salinity................

 

Xenia can be finicky at times, I had xenia in a two month old 15gal nano before and they would melt away in a week, all parameters were OK and tried Iodine also. It took the tank to aged to 8 months before I can keep any xenia!
I setup a 120 gal and in 6 week I have xenia and their thriving and growing like crazy! Try to figure that out!

 

I recently added a pulsing xenia to my tank after researching anything I could find on it. It the course of research every thing i read stated that it would stop pulsing if the ph dropped below 8.1-8.2 that it was the number 1 reason for xenia not doing well. Test the ph daytime and at night and make sure it doesn't drop below those parameters and hopefully it is just this small thing that is affecting it. They call xenia the tank ph barometer it is that reliable on dropping ph. Interesting tidbit......