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.
Chlorine concentrations in the range of 0.1 to 0.4 parts per million are usually maintained in municipal supplies, while ranges from 1 to 3 ppm are used in both pools and spas. Three types of chlorine can be measured: 1  Free chlorine â most effective as a disinfectant. 2  Combined chlorine â formed when free chlorine reacts with other compounds within the water. 3  Total chlorine â the sum of free and combined chlorine.