Might help to cut some off and place a white paper towel. What type of rock, dry or live?
With most macros i find removing as much as you can the best solution and increasing manual filtration swap out and marginal increase in water change schedule your best choice.
if no corals on the rock, do a water change and use the old water as holding and rinse water. Scrub with a stiff bristle brush outside the tank, dip every 5-10 minutes so rock stays wet. When done scrubbing apply h202 to the area that once had algae. Rinse in the bucket before returning. Has the smallest effect on tank equilibrium and also the quickest route, but most work.
Herbivores are hit or miss with most hairy algae. If it is bryopsis, fluconazole will be your best friend. Turf algaes can be a pain, only thing ive had reliably eat are turbos if i constantly trim back to the rock. Go slow with nutrient control and vibrant if go that route, to heavy handed and usually ends in cyano.
