Quote Originally Posted by yekalri View Post
07/05: pH>8.2, FC 0, TC 0, CH 250, TA 250, CYA 100
07/05: +4hr pH 7.6, FC 0, TC 0, CH 250, TA 200, CYA 50
07/06: pH 7.6, FC 0, TC 5, CH 250, TA 200, CYA 50
07/07: pH 7.6, FC 0, TC 5, CH 200, TA 200, CYA 0
07/08: pH 7.2, FC 0, TC >5, CH 200, TA 160, CYA 0
I don't know any way that CYA can go from 100 ppm to 0 ppm in 48 hours or less, without some MAJOR chemical manipulation. What happened? How are you testing for CYA?

Many water tests are not reliable. The reliable way to see how much chlorine demand your pool has, is to do a bucket test.