Brown algae growing on some of my frags

[SolarReefer]

Anyone know what this weird algae is? Nitrates were 50+ on my Red Sea test kit and my phosphates tested .04. Did a 20% water change yesterday and I come home today and there’s all this brown on my rocks. Tank is 5 months old and I thought I already passed the ugly stage. The brown on the rocks is new but the algae has been growing on the frag plugs for a few weeks

 

[blaxsun]

Could be green hair algae or dinos (hard to tell if the color is accurate in the image).