I feel I may have a problem so i wanted to perform an OCLT tonight. I brought my FC to shock value just because I'd like to for the night. When measuring FC I got 23, then I tested again just to see what I'd get; I got 24. So I decided to split the difference and go with 23.5. Just to see what I'd get if I checked FC a third time I did...21. Well, okay let's test again...22. If I am only allowed 1ppm change in FC over the night and my start FC is anywhere from 21-24ppm in the course of 10 minutes I am confused. Why am I getting such a varied FC with back to back checks and how am I suppose to be accurate within 1ppm in the morning?