if it is tuff sounds like coralline.post a pic mart!no, its on the glass and is very difficult to get off. Not like a plant - like a film of red something on my glass.
Cyano :
If it is difficult to remove then I would say it is not cyno. More than likely coraline although there are plenty other types of algae.no, its on the glass and is very difficult to get off. Not like a plant - like a film of red something on my glass.