I saw a post on here about helping to verify my CYA test by substituting R-7065 for the pool water, in which case I should read CYA of 50. So I ordered some R-7065 today, and I assume the procedure is the same with the exception of substituting the standard solution for the pool water. The CYA instructions are to mix, wait at least 30 seconds, then see when the black dot disappears. My questions is, what if I wait 2 minutes, or 4 minutes, does that matter? The reason I ask is that I may need to put the tube under different light, over a different ground color, or pour the solution back and forth between the mixing container and the CYA tube until I'm confident of the conditions that I'm reading the CYA of 50, and then use these conditions for the pool water test.