Well my friend got back to me today and this is what he has found out... Looks like that powder he was telling me about was Fenbendazole. It takes care of ascarids (roundworms) including the threadworms, it is also effective against the flatworms too. This is also a good broad spectrum dewormer , so that you can preserve the bacterial flora within your coral. Another product is called Ivermectin. This drug comes in an injectable form, it is a thick oily solution (NOT SURE THAT IS GOOD??) . One problem is that Ivomec is light sensitive so long exposure to light can deactivate the medication. This is a very common drug (it is the active ingredient in Heartgard the heartworm preventative) you want the bovine form which would be easy to mix in water. Please keep in mind that he has no idea what these products will do to coral, so try it out on something small at first. He could not find any of that Levamisol in his cabinets, but said to look for both those drugs at the