Google isn't telling me much on this topic. I have the luxury of being able to add snails and things one at a time, if need be, I just walk down and pick them off the rocks. I am day ten into the cycle, ammonia and nitrites 0, nitrates came down to 5, brown algae starting up. Would you put in a few small snails and limpets? Maybe one a day? I want to bring the bioload up slooooooowly. Not planning on fish for a while.