"Just double checked my math with BleachCalc and it said it would take 3 cups, which is 24 oz. of 5.25% beach to raise 1000 gal. 10 ppm, 2 cups and 5 oz (21 oz) of 6%, and 1 cup and 2 oz (10 oz) of 12.5%. "

So according to that it would take 1 1/2 gals of 5.25% bleach to equal 1 pound of 65% cal hypo? Thats good information to have if your switching back and forth from bleach to cal hypo (like I do)..........