zoa issue

[brettm3535]

About a week ago I bought a frag of zoa's with approx 10 of them on the rock. I dripped them for about an hour and placed them into my tank. That evening and the next day they were all open and looking awsome. After that second day they have now got to the point that all were closed really tight. A few days ago I checked my water params aand all were good other than my calcuim was a little low. I also did a water change to see if this was the cause. Tonight I still seen no improvement so I did a little reading up and I determined that I would try putting them in a higher flow area. Since I have seen one of the pods has a skin like material that has blown off and now I am seeing some color and that paticular one is starting to open slightly.

Just seeing what this might be and is there anything else I can do to turn these things around?
Thanks