You might want to start just using bleach instead of cal-hypo.

You do need to keep shocking until two conditions are met:
1) You can go from sundown one evening to within an hour of sunrise the next morning without losing more than 1ppm of chlorine AND
2) You have no more than 0.5CC.

Then, we usually advise keeping the chlorine high for one additional day for added insurance and then let it drift down and keep it within the proper ranges based on your CYA level. A chart that explains the connection between CYA and chlorine can be found at the following link: http://pool9.net/cl-cya/

Have you tried the DE test yet so we can verify that your filter is working properly?