Algae taking over GSP

[Dreamstimer]

Please help me save my GSP, the algae seem to be taking over their spot. The tank is not overall affected, just in this area. The Xenias are thriving, though I'm constantly trimming them, could it be a side effect?

 

[Dreamstimer]

Image didn't attach, here is a screenshot:
http://scr.hu/2qc6/6dobm

PS: what is the brown thing in the foreground? it seems to grow slowly and it doesn't look to be coraline.

 

[Dreamstimer]

Later edit: tank is Fluval Edge 12g, 3 years. Just one goby and a shrimp, plus several corals.