If you use 6% bleach, each quart will add 1ppm of chlorine. If you use 8.25%, each quart will add 1.5ppm of chlorine. Since you water is cloudy and since you let it drop to zero, you will need to shock your pool. With a CYA of 50, your shock level is 15ppm so add enough bleach to take your chlorine that high. After you shock the pool, let the pump run for a few hours and then turn it off per Ben's instructions above.