It was helpful, thank you! Couple more questions...

Is the evening the best time for testing and adding chemicals?

If I'm only testing TC, I guess it's hard to know when I need to shock the pool since I won't know the CC value? Pool store tests for FC only, but their test only goes up to 5ppm, and they never dilute...they just report 5 . I might have to get me one of the DPD or FAS-DPD tests.

That's what I thought about the CYA/Chlorine interaction...if you have a higher CYA, you can get away with a higher Chlorine because you need it.