In your size pool, each gallon of 6% bleach will raise the FC by about 3 ppm, so if you're trying to achieve shock level, I'd put 7 gallons of bleach in it. Pour it slowly into the return stream, being careful not to splash it on your liner. I would do this at dusk, since the bleach will have all night without sun interference to start working on your water. In the morning, test again, and add whatever amount it takes to get it back up to 20. Do this 2-3 times a day, filter running and backwashing as needed, and it will clear up. It may take up to several days of this--fixing pool problems is almost never an overnight process--but it will clear. I would NOT use any more cal-hypo, though--your calcium is already way too high, and that in itself can create problems with milky water that are much, much harder to solve than just shocking with bleach.

Two of the cheapest online sources we've found for the Taylor kit are http://www.amatoind.com and http://www.spspools-spas.com. Leslie's online also sells a relabeled version of the same kit.

Welcome to the forum!

Janet