I'd been a bit slack in my testing and apparantly let me chlorine get a bit low. The pool clouded up some, and I assume it was an algae infestation that couldn't take entire control. I My CYA is around 40, so I used a shock level of 16. I have been doing the overnight test for about one week now. 7/25 pm FC 14.5, CC .5, 7/26 pm FC 15.0, CC .5. I figured that this was just a testing error, since I was within .5. 7/28 pm FC 10.5, CC 1.0, 7/29 FC 12.5, CC .5! Now I suppose the most reasonable thought is I somehow screwed up in testing last night. But is it possible for the chlorine to increase 2 hours overnight?
How long from additiion of cholrine should you test? Last night I added chlorine and then went out. When I got back about 2 1/2 hours later, the timer had shut off (forgot to tell LLP(lovely life partner)) to keep the pool running. I tested shortly after turning the pump back on. Could it be possible that the chlorine hadn't circulated enough and gave a false reading?