I have taking my pool samples to a pool store and they tested my cya and told me not to use tabs, to use liquid chlorine,well I took up a pool service and they installed a chlorinator with 5 3in tabs, so ask about what my pool store had told me, well the guy said that it was like 70ppm and that the tabs won't raise the cya that much only if you use it for the season and liquid the rest of the year. Question is he right! and how can i test it and how much ppm does the tabs raise the cya, is there a calulator for the 3inch tabs, the service is coming every other week to test and chemicals, thank you.