The best additive to keep algae under control is mariculture Live Rock and mature aquarium, possibly pods and definitely good CUC. Adding intermittently toothbrush or other brush, mostly to rock surface is also of great value.
I don’t have a large enough tank for those big grazers but my urchin, ninja star snails , ceriths, trochus, nassarius, conchs , emerald crab and hermits do a great job.