Hanna 8.2, Salifert 8.3 and near as I can tell you used the wrong dropper for the Red Sea alkalinity test (you use the small plastic dropper and count the number of drops - not how much you used or how much you have left). If there are markings on the tube you're using - that's not the right one. (Addendum: I have the Red Sea Marine Test Kit, and I'm looking right at the alkalinity test - just in case anyone was curious).