I am by no means an expert. I am putting this up for debate/discussion. I use the Salifert kit for Iodine. BUT, I do use some Seachem kits as well. I like the fact that the seachem kits come with a reference sample and when in doubt, I do run tests with the reference sample to be sure I am performing the test and reading it correctly. Anyone else have some input here? What kits do you use? What additives, if any?