Yeah, I would remove it from the Acan, it can't help anything.
With the Cephastreas, not really sure, I have mine in a pretty well lit area, and it's spreading nicely. I've read they are a low-med light coral, but I placed it before I knew this. And it's always looked good? Its under T5, but 780 watts of it, and it's about 10" under the surface of the water. Wish I could help more, but I don't know.
Here's a pic of mine as of today,
Original frag is the middle raised section, been in tank about 6 months.