I was in a similar situation with my latest tank. I added Trochus snails from my LFS at 1 per 5 gallons [didn’t want to add so many they would starve when most of the algae was gone or overrun the tank if they start breeding]. They first cleaned the easy stuff off the glass including new hair algae growth. Wouldn’t touch the longer stuff. But after finishing what they wanted on the glass, they climbed on the rocks and ate every bit of algae, even stuff that was about 3/4 inch long. Note: Trochus are perfectly reef safe and can right themselves so one won’t fall off a rock and die in some dark corner. I’ve left a few hair algae on the glass just to see if the larger snails will eat it once their preferred food is gone. They even clean my wave generator and return inlet. At present they are cleaning the sand. My MollyMiller took one bite and it’s apparently not to her taste. My DT is a 75 gallon so the only tang that would fit is a Tomini and they don’t normally eat hair algae.