Chemiclean oxidizes algae it is imperative that you ensure proper water oxygenation during use. I'd definitely up the amount of water movement especially at the surface and add more air volume to the tank if possible. I've used it in a small reef I had when I started in that addiction...lol. It works but if you don't get the reasons for the algae under control it will come back. Phosphates are the main culprit. I have no idea on how safe it is with rays, it didn't kill my corals.