Red algae???

[prisse67]

This stuff is red and some of it brushes off but does not blow off and some of it does not brush off. Tank is been up 3 years. Any ideas. I have battled Cyano since day one but only on the sand I do water changes bi weekly.
alk-9.5
Mg-1400
Calcium-425
Phos-.02
Nitrate-.05

 

[Rollman]

Resembles cyano