How much chlorine bleach would you need to treat 5000 gallons of pool water?

To shock the pool, about a gallon. To just chlorinate, a quarter gallon, then measure the chlorine level with an OTO test kit. Keep the chlorine level between 1-3 PPM, and the pH at 7.2. You can adjust pH with plain old baking soda if the pH is too low, or add a little muriatic acid if the pH is too high.