Check the listing for details. BioGuard Arctic Blue Shock 2 lb - 2 pack. Condition: New. Listed at 37.98 USD. Arctic Blue Winter Shock helps avoid costly spring problems such as algae, cloudy water, and high chlorine demand. This quick-dissolving, non-clouding product oxidizes organic wastes, provides chlorine protection, helps keep pool surfaces clean, and helps protect water during the off season months. May be used in swimming pools with all types of surfaces and filter systems. Product Benefits: Chlorinating-oxidizing treatment ideal for vinyl, painted and fiberglass pools Non-clouding Quick Dissolving Ideal for all pool surface types Dosage: Ensure all pool equipment is working properly Clean or backwash filters following manufacturer's directions Balance the water according to manufacturer's recommendations Adjust pH to between 7.4-7.6 Check for metals and if present, before using this product When using other products as outlined in the directions for this product, always follow directions on those products Use one pound of Artic Blue Winter Shock per 6,000 gallons of water Broadcast directly into the water in the deep end of the pool To prevent damage to pool surface, use a pool brush to disperse any un-dissolved granules which may have settled to the bottom of the pool Circulate water for several hours, or preferably overnight