Keep your chlorine at shock level (which is based on your CYA level) until you meet three criteria:

1) You can go from sundown one evening to within an hour of sunrise the next morning without losing more than 1ppm of FC
2) You have no greater than 0.5ppm of CC
3) Your pool shows no signs of algae

At that point, let the chlorine drift down but keep it in the range between minimum and maximum ALL the time.

This process may take a few days but you have to be diligent about it. Eventually, your chlorine demand will decrease.

This chart shows the relationship between CYA and chlorine:> http://pool9.net/cl-cya/