Setosa dying in spots

[SCReef'n]

I just noticed this spot. Not sure what has caused it or how long it’s gone unnoticed. Parameters as of today

1.026 sg
15 no3
.04 po4
8.2 dkh
440ca
1305 mag

lights have been in alcimation mode for a week for some new frags. Everybody else seems normal. Thoughts?

 

[DSC reef]

Hard to see in blue light but is that bubble algae on the rock? It looks like it could be bothering it where the montipora is trying to encrust. I just can't see it well enough to be positive.

 

[SCReef'n]

Ok better pics. Also there seems to be anohh th ER spot on the end of one branch. I did notice a tube worm below the original spot and glued him shut. Hope that was it but doesn’t explain the second spot

 

[DSC reef]

Definitely no bubble algae, lol. Hard to say about the small spot where it's encrusting but the rest of the coral looks fine to me.

 

[TopShelfAquatics]

I would look around for monti eating nudis. I dont think the second spot is more death it might just be new growth.
Have you used aiptasia X around the tank lately? It can burn corals like that if a piece flies away from what you're trying to kill.

 

[SCReef'n]

No aptasia thank goodness. I will look for nudibranchs. Hopefully it won’t spread

 

[Sampson42084]

No aptasia thank goodness. I will look for nudibranchs. Hopefully it won’t spread

I'm dealing with a similar spot on my setosa what happened with yours?