Enough for 3,000 ppm (parts per million) as a starting point. So depending on the initial salt level of your water, you only add the amount needed to establish 3,000 ppm. For new pools or freshly filled pools, the salt level will most likely be zero. In this case, 50lbs of salt per 2,000 gallons of water will establish 3,000 ppm. For existing pools, the previous usage of chlorine bleach or tablets will have already introduced a level of salt into the water. Have the water tested first then add the appropriate amount to establish 3,000 ppm.