How much chlorine bleach to add 639 gal of pool water shock water?

To calculate the amount of chlorine bleach needed to shock 639 gallons of pool water, you can use the following formula:

Amount of chlorine bleach (in gallons) = Volume of pool water (in gallons) x Desired chlorine level (in ppm) / Chlorine concentration of the bleach (in ppm)

In this case, let's assume you want to achieve a chlorine level of 10 ppm and the chlorine concentration of your bleach is 6.0% (or 60,000 ppm). Plugging these values into the formula, we get:

Amount of chlorine bleach (in gallons) = 639 gal x 10 ppm / 60,000 ppm = 0.1065 gallons

Therefore, you would need approximately 0.1065 gallons (or about 1 cup) of chlorine bleach to shock 639 gallons of pool water.

It's important to note that this calculation is just an estimate, and the actual amount of bleach you need may vary depending on factors such as the temperature and pH of your pool water. Always follow the instructions on the bleach label and consult with a pool professional if you have any doubts.