This forum has taught me many things about managing reefs, and I'm grateful. Maybe my experience with flatworms can help others with the nasty critters. I have 100 & 75 reefs. Weeks back, I probably had at least a couple thousand in the 100, and most recently a small amount in the 75. Over a period of several weeks I constantly extracted them with a turkey baster. I got experienced enough to even remove them from the gravel. I had a net setup in the overflow to receive them so no water was lost in the aquarium. As an alternative, I would also blast them off the coral with the baster and net them. I got a lot of action with this method. At any rate, after several weeks I reduced them to a manageable group to use Flatworm eXit. As you know, it is the body fluids of the flatworms that cause reef problems. I used the manufacture's recommended amount directly into a high flow area of the tank, and they started dying immediately. I used a series of nets to remove the dead. As they die, they float freely about the tank. The results were that the entire reef, corals, fish, shrimp, etc. were not distrubed in any way, and the flatworms are no more. I never used any carbon. This did take some effort, but it was well worth it. At least I'll know how to handle it if there is a next time.