Coral closed after a week

I bought a small zoa frag a week ago and it was fine untill yesterday it was completely closed. On monday i added a small nepthea tree coral and it has still yet to open up like it was in the store. Tank parameters are as followed
Calcium 280 i am using liquid calcium to raise it
Phosphate 0
Dkh 8
Ammonia 0
Nitrite 0
Nitrate 0
Ph 8.3
Could it be from the calcium being a little low?