1 lbs of pure chlorine is about 1 gallon of 12.5% chlorine.

So ppm for Bleach is:

ppm = Gallons Bleach * (% Hypochlorite / 100) / Pool Volume (Gallons) * 1,000,000

ppm in lbs

ppm = lbs * (% Hypochlorite / 100) * .125 / Pool Volume (Gallons) * 1,000,000

Hope that helps.