This is the only stuff that I have ever tried that genuinely gets rid of Black Beard Algae. As you can see from the picture within a couple of days it goes red and dies and the fish start eating it. You have to be patient treating the tank, as in my 240L aquarium I can only dose 6ml per 24 hours. Some of the hard scape you can remove and dose and then leave it for a bit outside the tank, before returning. I can’t recommend this treatment enough. Very fast delivery excellent.