Help figure out

[popeye5683]

So have had this issue for last 3 months. Established tank of over 10 years. Looks like cyan but local FS looked under microscope. Pics and video attached. Chen clean doesn’t work. Used 2 bottles and no change . Sheets like cyan but is a bit fiberous. Has anyone seen this and what do I do. It’s taken over my tank. All levels are good .

 

[Moe K]

Can you blow it off the rocks? Don't know what that huge dark spot at the top of the slide is but the rest of it looks like cyano.