I don't think it's the Iodine itself that is coating your tub. Our water here will leave a pinkish orange residue in the tub or toilet if you don't clean often enough (we have very hard water), and has been doing that LONG before I ever started trying to detox or use Iodine. And since you didn't notice a residue before taking Iodine, I definitely think it's a detox residue, just doubt it's the Iodine itself. I'm thinking it's like our pink/orange residue ... something that really shouldn't be there, excess iron, or other minerals. I've been told most of our pink/orange is iron. I'm betting your body is still probably using most of the Iodine you are giving it. Also consider, once exposed to air, for what is not absorbed, your Lugol's will turn white eventually unless exposed to peroxide.