as long as the product is used carefully(i.e dissolved in tankwater before pouring into ideally the sump of the tank to be safe), it is pretty reef-safe. it’s essentially balls of hydrogen peroxide. that said i wouldn’t dump it in the dt when undissolved as the balls have caused bleaching in my anemone and killed one of my mushrooms when some landed on them. so i would say it’s yet another “reef safe with caution” thingamabob in this hobby hahahaha. it does help with managing ich though, at least from my experience. Velvet? another animal altogether. Sent from Singapore Reef Club mobile app