Hey Spidey!
Everybody is correct per the product claims.
Iodine based dips "claim" to remove/ kill flatworms, and I have yet to verify.
I do dip every coral in a flatworm exit dip. 2 drops FE to one gallon of water. Let it sit for 15 minutes. If I actually SEE flatworms, I dump the water and redip for another bout of 15 minutes using a turkey baster to blow the water in and out of every crevice.
If I do not, then I'm done.
Iodine is also a good dip, but it targets more your bacterial infections which are common in corals after shipping, handling, and fragging.
I have an iodine dip here that specifically claims it will remove and kill flatworms. But again, I've never verified. Maybe if I get a FE infested coral, I'll try it and see if it really works.