Help! What is eating my soft coral?

[ifwisheswerefishes]

Look at the white patches on several areas of my coral. It looks like something may be eating on it. What would it be and how to get rid of the pest? This coral is attached to my base rock and I cannot remove the coral to dip it. Any suggestions please?
All my other softies are not having the same problem. Just the one.
Thanks in advance

 

[itsken37]

Remove entire base rock? or is it too big?

 

[ifwisheswerefishes]

Base rock is too big.

 

[itsken37]

See any of these?

 

[ifwisheswerefishes]

See any of these?

No I do not. I even go looking at night.

 

[itsken37]

Prob water conditions then. Some softies are pretty touchy.