The greatest result of these "Non Chlorine Shocks" in an outdoor pool are measured in the amount of dollars leaving your wallet....

Shocking is simply raising your Free Chlorine (FC) level high enough to kill off any Combined Chlorine (CC) which is the used up by products of the FC doing it's job. Yes, use chlorine to shock, preferably liquid and most find regular ole 6% ultra bleach is the easiest and cheapest way to go.

Dave

P.S.- I've now only "shocked" once this entire season, since April 1st. If you stay ahead (as CarlD says) you shouldn't have to "shock" very often.