OK, thanks again. You've been a great help. I normally do not use the pucks unless my cya gets a little low. I normally like to keep it around 35-40. Probably a couple of times total in the summer, I end up having to add a couple of pucks to bring it back up, but that's it. Since my cya tested at 0, I don't think the few pucks I have in there now will raise it too much. In fact, I expect that I may need to add a few more, but will definitely do it slowly. Thanks again for the great tips. The pool is blue again and I'm a happy camper.