SPS issues?..

[ashr]

Hey all

So I have noticed a few issues with some of my SPS corals. They are losing color on some spots and turning white.. but it does not look like a bleaching white.. kinda off color, if that makes sense. I noticed it on one of the corals.. it looks to be moving slow so I didnt think it was white death or anything. I dont know if its RTN though..(does not seem to be melting off or anything..)

EDIT: I am pretty sure it is not RTN. This is slow and more like off blotches
EDIT 2: I have started to dose a new bottle of "Kent Mg"
New ATI lights, couple months old
Cal 400,ALK 6-7,SALT G 1.24 and mag is around 1250.


Not sure what I should do.. Watch if it gets worse and frag? Any ideas? I could try and get pictures but they are bad angles and not sure if you would see much.. Kinda lost here..