[mps9506]

Ditto to what DaddyJax said. The colonies tend to grow pretty thick and it is difficult to get flow all the way through the colony without ripping the tissue off the outside branches. I have seen them RTN very rapidly, usually full colonies. Although it can be difficult to tell exactly what caused it. But frags and smaller colonies seem hardy providing the correct tank conditions.

But before you introduce any other SPS I would really recomend getting your Ca down to 400-450 (depends who you ask). Get a quality alk test and find out where that is sitting. This will help you out a lot with getting your sps to grow quickly and minimize your future losses.