I have been using pucks since I opened my pool to get the CYA level up and plan to stop once they are close to right. I tested today and with a full vile I can still make out the black dot vaguely. So I'm guessing that my level is still less than 30 and can use a few more pucks until the CYA increases. Is this a safe assumption. I only have the HTH 6 way test kit.