How do I shock my pool to breakpoint chlorination?

Shock to 10x your combined chlorine level, or just raise free chlorine to 10 ppm if you don’t know your combined chlorine. For a typical 20,000 gallon pool, that’s about 2 gallons of 10% liquid chlorine or one pound of calcium hypochlorite shock per 10,000 gallons. Do it at night, run the pump overnight, and test the next morning. If the water turns from dull to sparkling, you hit it.