Had a massive outbreak years ago in my FOWLR. I upgraded my skimmer, used lots of GFO and many water changes with good RODI water. Inbetween water changes I removed as much as I could manually. Eventually, the algae starved.
What didn't work: more flow, new lightbulbs, snails, crabs, tangs, foxface.
What didn't work: more flow, new lightbulbs, snails, crabs, tangs, foxface.