If it comes off and looks like dust it's probably diatoms. I had a MAJOR bloom (everything was solid brown!!) in my 90 gallon when I upgraded my lighting and after a month or two of dusting off the glass and my plants during frequent small water changes they went away. They aren't usually long lasting and will go away.
Sent from my iPhone using Aquarium Advice
Blackbeard algae looks like a long, scraggly beard....I didn't know for a long time either- but that's the best analogy I have for it lol!
Sent from my iPhone using Aquarium Advice