0 everything is your goal to a degree. I fyi have 0 iodine - and no symptoms - it means you're in balance - the things using iodine are using it and you're supplying it."Not sure" should be an option.
I got back an ICP test that showed I had 0 iodine and low boron in my tank.... should I care? I'm not sure. I do 10-15% AWC weekly, so it should be getting replenished, not sure if I should be dosing additionally or not.