I did a partial drain about a month ago. Got my cya down to about 85. I haven’t put anything in other than Liquid chlorine and some Lo and Slow ph reducer. I test the cya this morning and it read about a 100. Just took a sample to the pool store and they said it was 140. The use the Bioguard Alex system. Which one should I believe? With either number what could be making it go up? I use a Taylor k-2006 kit.