If you haven't already tried Bayer dipping, I highly recommend it. I have used it on many, many types of coral and have never had issue with it. It is cheap enough, you could dip whole large loads at a time. I will dip with something meant for coral...and see some critters die...and then add the Bayer and TONS of stuff floats off dead. It is impressive and seems totally safe. I have used it for a good while now and like it a lot. It's all I use for critter eradication now.