This is a discussion on API Master Kit. within the Beginner Freshwater Aquarium forums, part of the Freshwater Fish and Aquariums category; -->
So the other post going made me think of this.
I rmember Byron saying that the directioins for the nitrate test was not correct ...
when they say vigorously they mean vigorously problem is most people don't truly shake vigorously so its usually recommended to shake the bottle #2 for at least 2 minutes. I shake really good and still shake for 1-1:30 minutes, if its not well mixed then it will give you bad readings and eventually the bottle won't be much good anymore because you would have used too much of one ingredient over another so mixture wont be right.