When it's time to shock your spa, our Shock Gems are the convenient solution because the tiny one-ounce pods are specially formulated to work in conjunction with the SilkBalance water conditioner. We've taken the hassle out of keeping your spa clean with this new, handy, non-chlorine chemical alternative. ELIMINATE ODORS AND REDUCE ORGANIC CONTAMINANTS with these convenient, single-dose MPS shock gems Because SilkBalance is not a sanitizer, you still need to oxidize any organic contaminants in the spa. Simply toss one or two of these MPS shock gems (depending on bather load) in the hot tub after soaking to remove organics such as body oil and perspiration and you're ready for the next use. Use a single one-ounce gem (28 grams) per person per 500 gallons (1893 liters) or less, of spa or hot tub water.