I know this has been covered a million times and I have read almost every post on the subject. Since the readings are subjective at best I just got back in town. My wife been doing an amazing job with the pool and testing.
Her last CYA test was 60, 2 days ago. I tested this morning, bright full sun. At 60 and the dot starts disappearing, at 40 its no longer visible. What number should I go by?