Based upon what I've read thus far, it appears that the 9+ years of using chlorine sticks has built up a residual of CYA in my pool that is not allowing me to get to a chlorine level that I can measure....other than zero. I've ordered a new test kit (TF-100) but is there anything that can be done today before I can get a real measurement on CYA? Pool water is crystal clear; pH is 7.4-ish; TA is good too; Just absolutely no free chlorine. Also, if there is a thread that already handles this please direct me there...i just haven't found it yet. Thanks all. Tony; BTW, one heck of a site...I am looking forward to learning more and contributing when I can.