Here's some good reading for you (you really don't need to read anywhere else). You're not fighting CC, you're fighting organics. The last link is what you will want to use in the future to determine how much to add. If you don't have/use a smart phone or tablet, you can always use the browser version of Pool Math.
ABCs of Pool Water Chemistry
FC/CYA Levels
SLAM Process
PoolMath
ABCs of Pool Water Chemistry
FC/CYA Levels
SLAM Process
PoolMath