Right, the clean up crew, for this reason, is usually not that great of a concern. Well, I suppose some snails but there is probably always some algae growth for them. But hermits and other snails are clean up, as in "clean up leftovers" after feeding, or algae, or stuff on LR...they are more opportunistic. A lot of the angels need some algae but they are also generally "grazing" on stuff on the LR, including worms, crustaceans, sponges, algae, etc.
You don't want your LR covered with algae :nope: