Yes, I can understand and in fact do myself shake all the bottles and testing tubes. What I was wondering in particular was why a 30 second shake of the bottle and a 1 minute shake of the nitrate test after adding bottle 2. is required. Of course the test liquid has to be dispersed but as the liquid is not dense and the amount of water so small I was curious to know if there was a special reason for the attention to the shaking. It is what it is I supposemakes sure the particles in the test are thoroughly and evenly spread through the liquid so you get an even test. I actually shake all the tests prior to use.