Wondering if I can drain and add water at the same time. Just seems to make more sense time wise. I fear that my CYA levels are very high but don't have the test kit yet (ordered a Taylor kit from here). I've been using trichlor fast dissolve pucks since we had the 15 x 30 AG, 48" high pool installed last August. At the beginning of the season I was able to put two 1oz pucks in at night and wake up to a 2.0 a 3.0 reading. Now I've brought it up to 4 pucks and I'm lucky to have a 1.0 FC reading in the morning. At one point, a couple of weeks ago, my pH dipped to 6.8, although I understand that it could have been lower than that considering the test kit I have only goes down that low. I added a pH increaser and brought it back up and everything seemed ok but now not so much. I know I'm going to have to drain and add, but when I do can I do both at once?