The pH has a tendency to drop at night, that's why some people recommend dosing alk at night. I don't think it makes that much of a difference, really. I dose throughout the day and night, 8 separate doses a day. I have to, as I dose a total of 120 cc's each of 2 part a day

. I use the 3rd channel to dose mag, and since the volume for the corresponding mag is so small, I just dose it once a day.