I have a 24ft above ground & we fill to about 13500 gallons. Last year before we closed the CYA was very high. I use a Taylor K-2006 kit to test and the CYA reading wouldn't even make it to the 100 mark. We drained about 3/4 of the water before we closed last fall. So when we opened the other day we added that amount back in fresh water. I have only added one 1lb bag of calcium hypoclorite shock. After all that the CYA reading is still between 90 & 100. How is this possible after putting so much fresh water in? Do you think I am getting inaccurate test results? I don't know what to do next. Free chlorone is 5.6, pH is 8.0, calcium hardness 200 & alkalinity 120.