You can also use The Pool Calculator to calculate dosing. You will see that one gallon of 6% bleach raises the FC by 6.17 ppm in 10,000 gallons since 6.17 is the "trade %" which is the % available chlorine by volume. 6% is the weight % of sodium hypochlorite itself as found in an ingredients list and 5.7% is the "% available chlorine" (by weight) which is also printed on Clorox bleach bottles. Yes, all these different units of measurement are confusing but fortunately they are close enough to one another to just go by a simple rule-of-thumb.