API is alittle high, don't worry about multiplying or division, everyone will get it when you post a Q about Trates. Salifert is pretty good and the Digitals are good.Sigh....trying to gather all info b4 starting my tank...so to be able to communicate in a common and sensible manner lol which test kit(with out having to have an understanding of quantum mechanics) would give me numbers that the majority of people can offer advice about?