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.
In water and wastewater treatment operations, ferric chloride is used as coagulants or flocculants for odor control, phosphorus removal and hydrogen sulphide minimization. This is one of the few water treatment chemicals that can sequester odors.