Also, trichlor pucks are stabilized which means they add CYA. So, if you are going to continue to use them, you'll need to check your CYA every week or two. For every 10ppm of chlorine that the pucks add, they also add 6ppm of CYA. When your CYA hits about 50, you'll need to stop using them or your CYA level will get too high. At that point, just use bleach for your daily chlorination needs as well as shocking when necessary. (I rarely shock my pool. As long as you don't let your cl level fall lower than the minimum on the range listed in the Best Guess chart, you shouldn't need to shock.)