I have 2 Ancistrus (Bristlenose) plecos they are about 4 inches. I drop a couple algae wafers in there every night after lights out,. I am in the same boat now you are in now, I have virtually no algae. Without knowing how big your plecos are I would drop probably 4 wafers for the plecos and otos every day to every other day at lights out. Occasionally you can supplement with boiled zucchini or some other green food. You don't want them to feed too much because you want the otos to pick algae off your plant leaves, they are good for that.

Fred