help live rock

[Craigdillman]

Yea as above post us some details about your system

How old ?
Hog big ?
What lights ?
What are parameters ?
Any live stock yet?

This will help us answer your question , my gut feeling is tank is super new and cycling and coralline can die out a bit or lights are a lot brighter than tank you bought live rock from and its bleaching both are fine , but If it's been running for a while and this starting to happen different story