Algae or not algea?

[DePinchGonze]

Tank has been cycled for 1.5 months now, no fish, just CUC. Had a short diatom bloom until I added GFO and carbon. Past couple day noticed this stringy thread like algea speeding on the rock.

 

[DePinchGonze]

Another picture

 

[DePinchGonze]

Bump, any ideas?

 

[rt67ghy]

Very hard to see anything from the pic. What are your nitrates and phosphates at?

 

[DePinchGonze]

NO3-5
PO4- 0.5

It's the white stringy stuff