Nothing eats cyanobacteria as far as I have seen, and you don't ever want to put anything in the refugium that consumes algae. As Hank stated, it's counter productive.
That said, a friend just started a tank with the reef saver rock from BRS and even though he cycled it in a separate container, the fish died when exposed to it. No ammonia was present, so it was not the lack of bacteria. I think this rock can leach something harmful. he mentioned his ph was fine as well, so, not sure what it could be at this point.