At CYA of 60, your chlorine needs to stay at a minimum of 5 at all times. Your best bet is to test your water daily, and add whatever amount you need to get back to 5-10 ppm. If you'll search the forum for mwsmith's posts, there is a link to a calculator in his sig that will help you figure out how much to add, based on your gallonage. It's generally best to add it at dusk or later, so it doesn't get consumed by the sun, and it has all night to work in your pool. AFter a few weeks of daily testing and additions, you'll get a good feel for your pool and how often you're going to need to add chlorine.

Janet