OTOH, if you can handle or need the extra calcium, cal-hypo is pretty cheap in the 90 lb buckets. I would never buy it in the 1 lb packets, too pricey. It keeps well in the heat and so is a good thing to have on hand for infrequent shocking. But only if your CH does not tend to run high. 64 oz will take me to shock level (from 3 to 18 FC) and raise CH by 11 ppm. For a serious problem where a lot of FC was needed over a long time, I'd still use primarily bleach, but cal-hypo 73% from Leslie's Power Powder Pro is great for a short duration thing.