Ground ginger!!! Sprinkle ground ginger in your reef tank next time you have ich. Ginger is used in some countries when people have a parasite in there intestinal tract which it cures. I've heard about this awhile ago so I decided to give it it shot and the ich cleared off the fish the next morning completely and I haven't seen it since.
https://reefs.com/forum/reefs-magazine/77954-skeptical-reefkeeping-richard-ross.html