Algae identification help!

[newbie321]

Any ideas what this could be? It comes off quite easily with a little rub but it seems to be spreading everywhere.
PH:8.0
Ammonia:0
Nitrite:0
Nitrate:0
2 ocellaris clownfish
1 Royal gramma baslet
1 coral banded shrimp
40 pounds live rock
50 gallon bowfront
Running Purigan, biomax, fluval media rings, and activated carbon.
Tank is around 2 months old. Was previously established by different owner.

 

[Sniperhank]

Cyanobacteria. A sign of excess nutrients and low flow in the system. The articles in my signature will help you work through this.