If you keep the pH on the high end (7.8), you should be able to chlorinate with cal-hypo until you reach your calcium goal. It will take a while. Each pound of 53% cal-hypo should raise your FC by a little less than 6 and raise the CH by 4. Don't dump 8lbs all in at once, use it as your primary source of chlorine until you reach your CH goal. By my figuring, you'll need to use up more like 30lbs of 53% cal-hypo to get above 200ppm.