Just out of curiosity......does anyone have any idea how much FC could be "consumed" after heavy rains sweep over a screened in pool enclosure? I'm talking about 2+ inches bringing in God knows what trapped on the screens over the pool. I still think that may be what lowered my FC below target and allowed further contamination. I only run my chlorine generator about 9 hours per day. This time of year I may have to re-think that. Maybe add some time overnight. And no, I don't have a VS pump. Maybe someday.