Thank you so much!!!agree, those also tell me it's derbesia.
I once convinced myself that my GHA was something different because it was so distasteful to everything and I didn't see those little dark spores. So I emailed an academic phycologist... who sent me a few papers and told me it was just plain old derbesia.
So yeah, I asked a professional seaweed expert to look at ... GHA. lol.
update us on how that tang does with your tank GHA.
The Desjardini tang needs the algae to be free floating to eat it. It’s not picking at the rocks yet.
I believe with time it will start picking at them directly. For now; I can brush them, tweeze them, and pick them off.
I’m tempted to add a foxface temporarily to help handle the hair algae.
My experience matches yours: most herbivores do not like derbesia.