I agree that the Hanna checker is the best bet ( for now) but Beananmials review on his website is dead on. You have to race the clock for no apparent reason, the results are displayed for a preposterous ten seconds( you better not get up to grab something from the fridge), and the sachets the reagent comes in are glued paper so you have to basically entirely separate the two ply packet to locate every remaining grain of testing powder. It works, and the testing is accurate but Hanna blew it in many aspects of this test.