You can go online at Costco.com and apply for a Costco Membership there by adding it to your shopping cart if you are shopping for the first time. Your membership card will be mailed to you within 7-10 days but you can actually shop at the online store immediately.
The three most common chlorine-containing substances used in water treatment are chlorine gas, sodium hypochlorite, and calcium hypochlorite.
The most common chemical used in the treatment of swimming pool water is chlorine. It not only. eliminates bacteria and algae by disinfecting (killing) action, it also oxidizes (chemically destroys) other materials such as dirt and chloramines.