I don't use a lot of liquid chlorine, but when I need it I want to get the best price for the % of chlorine. In the past I have used mostly Clorox, which I understand in 6%. I can get 15% Ch for $3.99/gal at Menards or 12.5% for $3.61/gal or 10% for $18.55/5gal. Clorox is $2.49 for 182oz at Sam's Club. How can I compare these prices?