The CYA test is part of the K2006.

You want to get rid of CC because in simple terms, it is chlorine that has already been "used up" and is no longer available to sanitize your pool.

It is ok to use dichlor for awhile if your CYA level isn't too high since it adds CYA as well as chlorine. This is one reason we need to know your CYA level. It is also acidic so if your pH drops below 7.2, you'll want to raise it by adding some Borax.

Don't worry about asking so many questions. That's why we are here!