From the standpoint of the tank if we pretend the box is an organism, it makes sense. Algae is part of it and it takes time to develop, and time for conditions to be right for it. The only neat, crisp tanks are brand new ones.I’m going to try 5hrs in total a day. The aquatic store recommended 6 when I got the tank. It’s weird that I only had this issue 5 months into having the tank, I thought everything was pretty settled. I’m half-minded to rip all the moss out (which it’s mostly attached to) buy new moss and start again.
If you're patient, black beard is just a phase, and it goes away.
Peroxide is effective, but remember, it kills the good and the bad, and solves nothing. I load up pipettes to kill hydra, and it's a great tool. I've never used it on algae.