Unless you're having an algae problem that absolutely cannot be killed, I would not worry about phosphates--they are the latest and greatest way to separate you from your money by convincing you to add something to your water that you don't really need. As for the CYA not showing up, you didn't say whether you broadcasted it or put it in the skimmer, but it generally takes a week or so before it dissolves enough to show a testable level.

Janet