From the advertising - "Dino X works against dinoflagellates, bryopsis, and many other types of plague algae with no ill effects to corals."
Says to me it's is sold as meant to affect other algae
PO4 has always been low, NO3, always high. Yes RO, 50% water changes every 2 weeks. I think that's more than enough. Always run media for PO4 AND use fozdown, carbon full time, tried pellets, currently running zeo again. Nothing dents this algae, my rabbitfish won't even touch it. Some herbivore he turned out to be -lol