My cylinders are not right I have to measure my water in another way, I use a syringe or a child's medicine measurer. I like the test kit very disappointed that I have to measure with syringe first. Not having the right amount of water in the sample alters what your ppm is, at least that is my opinion others say it does not matter.
Like all advice you have to take what is good and discard the rest. So far the good out weighs the bad on this forum.