After many attempts to get ahead of the algae with little progress, I have done a complete blackout.

 

I did a 4 day blackout after a thorough cleaning. The before and after pictures above don’t do it justice. The hair algae has disappeared!

Note that my prior attempts to deal with the algae was the more standard approach… manual removal of algae, water changes, and Seachem Flourish Excel. That kept the algae at a reduced level for the week; however, it continued to reemerge even after various tweaks to the lighting, nutrients, and CO2.

After the blackout, I plan on keeping everything else equal to see if the hair algae will reestablish itself. But so far so good!