You can test the strength of the liquid chlorine yourself. Simply add 1 ml of the LC to 10 liters of CLEAR water (5 soda jugs).

Or, if you have Ben's older PS232 kit, there's a 1.8ml measure--add that much to 5 gallons of clear water--a standard bucket.

Use Ben's FAS-DPD to measure the chlorine concentration in the 10 liters or 5 gallons. If you get 12.5ppm, then your LC is 12.5%. If you get 10ppm, it's 10%.

Carboys may be marked 12.5% and be anything from 10% to 14.5%--but if you just got the carboy, and it's below 10% go back to the pool store and complain--they aren't storing it correctly and you aren't getting your money's worth.

I just discovered this season they make a spigot for the carboys. But boy, did I feel DUMB that I never noticed it before! It makes life SO much easier!