I've had good luck with the HTH pucks and the Sam's Club brand pucks - i guess they're all about the same. You're smart to keep your eye on your CYA level. There is a tremendous amount of disagreement on how much is too much -- some folks say 30-50ppm is ideal, and that has been the conventional wisdom for some time. My pool is about 80ppm, and I've never had a problem at all. I use a chlorine puck or two in a floater at all times...just in case...but I normally add chlorine by using wal-mart ultra bleach. I just like having a puck or two floating in the pool in case I forget to check the level for a couple days and it drops too low.