Thanks for the additional link. The useful number for bleach and chlorinating liquid is neither the weight percent of sodium hypochlorite (NaOCl) nor the % Available Chlorine which is the weight percent of chlorine gas (Cl
2) equivalent, but rather the Trade percent which is the volume percent of chlorine gas equivalent. This is dependent on the density of the product.
Trade % = (Weight % NaOCl) * (Specific Gravity) * (Cl
2 g/mole) / (NaOCl g/mole) = 6.15% * 1.1 * 70.906 / 74.4422 = 6.44%
However, according to their dilution table
here, the implied ppm of full-strength is 2500 / (6/128) = 53,333 or 200 / ((2.5/6)/128) = 61440 or 200 / (0.5/128) = 51,200. A 6.44% Trade would be 64,400 full strength so there is an inconsistency here. Using the Trade %, one gets the very simple rule that one gallon in 10,000 gallons raises the FC ppm by the same amount as the Trade % value so in this case that would be 6.44 ppm FC. By comparison, 6% bleach is 6.17% Trade (using 1.08 density).
The best thing to do if one uses this product is to just measure the result in the pool.
By the way, chlorinating liquid is usually measured in Trade % which makes the calculations direct and straightforward, though the error is not large in any event.
Richard