i have a 17k+ gallon ABG. my CYA reading was 10 at best a couple months ago. according to the pool pal calc, i needed to add a little over 4lbs of CYA to come up to around 50... i did that 2 months ago at the beginning of the season. it hasn't budged. still reading 10 at best, i dumped another 4ish lbs in there 2 wks ago... checked again today... still 10 at best... my reagents are new every year and i've never had this problem... i have the 50ppm reagent to test and show what 50 is supposed to be so i can work off of that (that looks and works fine)... but with my pool water is still pretty much clear all the way to the top of the tube... before i dump another 4lbs in, i wanted to see if i could possibly be doing something wrong.