clams dont need iodine. besides that NSW levels of iodine are around 6 PPB. thats like nothing, if you counted and categorized every molecule of sea water, when you got to 1 billion you would have found 6 molecules iodine (iodide actually).
hobby test kits CANT detect iodine. a few years back i took a water sample to a local lab to have it tested for metals ect.. i also had them test for all major and trace elements. the chemist had to send out a separate sample to another lab out of state to test for iodide, the iodide test alone was $200 (ICP test) i asked the chemist about hobby test kits, he got a good chuckle out of that. dont waste your money on these test kits or dosing iodine.