I just tested my CYA for the first time since last summer when I brought it down to about 40-50 ppm through draining and refilling. I used the Taylor kit to test and felt like I had good results. When I tested the same way today, it registered essentially 0ppm (solution was totally clear). Could the reagent have gone bad? My kit is no more than 2 years old, I think about a year. I'm assuming there's no chance the CYA dropped like that over the winter with minimal water topping off.