What is this growing on my monti shelf?

[splix]

There has been this brown/clear stringey type stuff, almost a slime but not very attached to the coral. I can take my finger and flick it under the water around the monti and the stuff flys off. It's been growing back after I do this. Is it an algae? It seems to be only on my purple shelf in the rear on the pink shelf up front.
It's got good flow and it's towards the top of the tank.

Tried to get a good pic but it started to get dark outside so lights went low.
You can see it on the very far right edge of the purple in the rear, also along the back behind the pink lemonade.

 

[reef bloke]

It's probably diatom or a slime algae, I hate to say it but your corals look a little sick and bleached in the image so something may be out of whack and allowing slime algae to grow on small areas of die back.

What are your chemical parameters and lighting?

 

[splix]

No doubt they're a little bleached but these guys arent bad. A lot of it is due to me trying to take a cell phone pick with low light. My tank pics always come out totally messed up because i'm trying to use a cell phone.
In the day they have color but they're not super vibrant.
Tank parameters are in check. 1.026/8.5 dkh/ 500 cal/ 1480 mag/ 80'. I check it about every day.

I did screw them up pretty bad with lighting on very high for about a week due to me being an new idiot when I first got them but I've learned and since have fixed it and they've been slowly coming back.

 

[splix]

Better day light pic

 

[MBMAX]

The brown part is dead already and the other parts are bleached .
The acro doesn't look good either .
.

 

[splix]

What would be my next course of action in this situation? let it go and run it's course?

 

[splix]

I've got other corals growing very well, it's just these pieces having issues. I wonder if it's a nudibranch?

 

[Reef Frog]

What would be my next course of action in this situation? let it go and run it's course?

I've read a few comments that lays the blame for STN/LTN on a bacterial source, and have heard of treatment with a dip of ampicillin or perhaps other antibiotics made specifically for aquarium use.

I have no idea if this malady is bacterial in nature or if such a treatment is advisable, but I find it's possible use for a dip or in QT is intriguing.

 

[splix]

I wouldnt be against dipping it but the fact that it's on a massive piece of live rock sort of rules it out I believe.
I've heard it's not advisable to dip anything on live rock, but I could be wrong.
either way, I cant get it out of the tank without a massive headache because it's on a large support rock. I really do care about everything in my aquarium so to see it go is saddening and if there is something I can do to help save it I'm all for it, but it needs to be full DT safe treatments unfortunately.

 

[A1t2o]

Break the dead parts off so that some of the live part goes with it and discard it. The clean break should prevent the dead area from spreading.

 

[splix]

Break the dead parts off so that some of the live part goes with it and discard it. The clean break should prevent the dead area from spreading.

Kind of what I was thinking of doing.