I have a 34,500 gal pool in FL. I was running a Total Control system with a CC-15 cell that I switched about 1 month ago to percentage & ph due to my ORP control not functioning well.
3 times now I have had 25ppm -40 ppm of CYA rapidly go to 0ppm.
Most recently I have been very stable at these readings, starting about 1 week after adding CYA
Total Control set @ 51%
FC: 5.5-6ppm, pH: 7.5, CYA: 40 ppm, TA: 40, CH: 380 ppm
Today, 5 days after my last CYA reading all those tested the same, but CYA reading (I tried 3 times) was 0 ppm. It makes no sense to me as previously, low CYA would have caused the FC to drop to 1.0-2.0ppm even with the salt system set to 100%.
I can not imagine any bacteria could have done this. What is consuming my CYA?
Any ideas out there.