Scrub the walls and let it settle and then do a water change vacuuming up the leftovers.
Next add enough Ca, Sr, Mn etc
Herbivores are often like us, they like tender fresh juvenile algae, not old tough adult algae. There's more nutrients in the young algae.
Cleaning tanks walls is needed every so often so it's not a bad thing to do and is much better than picking it off a rock, plant etc.
But the fact or the matter is that the herbivores are much more effective against the new growth than established growth. Make it easier for them to goggle up everything and keep on top of it.
Also they preferencially select for the Macro algae by converting algae into NH4/PO4 at low levels to now feed the macro/algae plants.
Regards,
Tom Barr