Will read much lower than your actual level. By Randall on 8/8/2017
Randall wouldn't recommend this product to a friend
Over the past couple of months, I've purchased and evaluated most of the hobbyist-level marine test kits from Red Sea, Salifert, Elos, Hanna, Nyos, SeaChem, Giesemann, Lamotte, and Hach, and then compared them to results from simultaneous water samples sent to Triton Labs for spectroscopy.
Regarding Iodine testing, ALL of the available test kits will give you inaccurate results even when performed correctly. In many cases, the test will read as 0 or low iodine when in fact your level may be dangerously high already. Many Salifert tests are excellent, and I had high hopes for this one, but it turned out to be literally worse than useless, as it encourages accidental overdosage.