What's on my corals!?

[nonagon13]

Help polyp extension looks poor on this coral (some sort of birds nest I think) and I notice these dark spots.

A bird of paradise was next to it in the same spot, had some polyp reduction but no spots. I had the birds nest corals higher up in the tank closer to the wavemaker and moved them down in case there was to much flow but they haven't improved much in the past few days.

My parameters are good, other sps such as green slimer and Walt disney are happy with good polyp extension. Should I dip the birds nest corals?

 

[Graffiti Spot]

Looks like the flow could have peeled some flesh off the coral. I would leave it be and let it heal. If it starts peeling more then I would cut it down to healthy branches and start over from the small pieces.

 

[Jettareefer223]

My green birdsnest does the same thing when something’s off just very tip appears to die off and has the brown/black algae. It’s my canary coral it’s the first to get upset before any of my acros including my Walt Disney. If you aren’t running carbon put some in and do a 5-10% w/c. Like others said just watch it. I wouldn’t dip it once birdsnest/stylos/pocci’s get upset dipping will make it rtn quickly..

 

[vetteguy53081]

Could be from shading (area that is blocked by branches giving that area little light)