Just keep in mind that adding dichlor and therefore CYA will increase the minimum chlorine level needed to both maintain and shock your pool. You would be better served to shock with liquid chlorine from a pool store (if you live in FL or CA where such things are common and cheap) or use plain unscented household bleach. Don't get the "splash free" stuff. The ingredients should be sodium hypochlorite. Very cheap from the grocery store or even a wal-mart.

How deep is your pool and what is your current CYA level? With the diameter and depth you can determine volume. That, the CYA level and the "%" of bleach (for example it might say 6% sodium hypochlorite) can be used to determine how much you'll have to add in order to shock.