We had a party at our house yesterday, so I raised our FC the night before in anticipation of the heavy swimmer load and the sunny, warm (85+) weather. My CYA is testing around 30-40, so I brought the FC to around 8, which is where it stood yesterday morning around 8 am.
We had 10 kids and 6 adults in the pool, some for as long as 6 hours. So I figured, between the sunlight and all the swimmers, I would have burned up a lot of chlorine. Yet when I tested at 8 pm, I was still showing a FC of 6, with no CC. That really surprised me. All I use as chlorine is Chlorox. My pH tested at 7.5 yesterday. I have not added anything else to the pool for weeks.