hsmyers said:So I shocked the pool last night. According to the pool calculator, I needed to add 6 gallons (of 10% chlorine) to go from 2 ppm to 30 ppm (22000g pool with 100 CYA). I did this and measured the chlorine 1 hour later. Instead of 30 ppm, I measured only 12 ppm. I measured it this morning: 12 ppm. I measured it tonight: 10 ppm (It was 95 degrees in So Cal today, so losing 2 ppm sounds about right). My SWG was off during this whole process.
What happened to all that chlorine? How could I go from 30 ppm to 12 ppm in an hour? BTW, the pool looked perfect prior to shocking (crystal clear, no measurable CC, no algae). The only reason I'm doing this is to try to understand why my SWG isn't working as well as it used to. Prior to all this, I had done an overnight FC test and there was no chlorine loss.
On a related note. Does anybody have any figures about how much chlorine an Aqau Rite T-Cell-15 should generate per hour?
I'm willing to bet money that the concentration of the 10% wasn't 10% at all, it had degraded and was much weaker.
There's a good chance you never reached 30ppm, and there's a good chance that IF there was something organic, it was immediately oxidized by your chlorine addition, and hopefully that took care of it....especially since you had no loss overnight and minimal loss during the day.