How much salt do you add to a 18x4 pool?

To determine how much salt to add to an 18x4 pool, you first need to know the pool's volume in gallons. An 18-foot diameter pool that is 4 feet deep has a volume of approximately 6,600 gallons. For a saltwater pool, a typical salinity level is around 3,000 to 3,500 parts per million (ppm), which usually requires about 40-50 pounds of salt per 1,000 gallons of water. Therefore, you would need approximately 260-330 pounds of salt for your pool.