I have similar problems in my aquascape. Blackbrush has popped up on the Bolbitis. It might be due to slow growth of the Bolbitis and extremely bright led light, light duration as well as plant metabolism of the co2 and nutrients, that may be causing it. I am considering of removing Bolbitis and substituting it with a slow growing plant where the leaves don't last as long as the Bolbitis. May be a cryptocoryne as a central plant?
What do you reckon?
I think its definitely to do with too much light in my tank, and lack of firtz for the plants (and not enough plants) . I've only had problems with green hair algae in my tanks, but never this black brushy beard stuff. first time running a CO2 & ADA soil as well.
I've read people chuck in really fast growing plants initially and once everything is balanced, they slowly change out to the plants they want to keep.
I think the Bolbitis looks nicer