What is this?

[KendonI]

I have a brownish red hair type algae that blows off the rock easier in some places than others. Under a microscope it is not Dino’s but other than that I have no idea what to do. I have a big clean up crew but it seems nothing I do helps. My corals are not dying and neither are my CUC and they seem to be eating some of it. Strange thing is my nitrates are double zeros. Do I dose nitrates or hold off? I don’t want zero nitrates in the water column but I also don’t want to fuel this outbreak. Please help

 

[Mr. Mojo Rising]

Everything in the picture is blue, I can't distinguish any brown. Can you please take another pic with the blue light turned off and leave only the white light on