The technical term for this substance is sodium bisulfate. It is a white, crystalline powder, and it is classified as hygroscopic. This means that it absorbs moisture from the air. PH minus is water soluble, and solutions that include it are considered acidic, with a pH balance of 1. When it’s called pH minus, sodium bisulfate is used to lower the pH levels in swimming pools. This substance can also help prevent scaling and cloudy water when applied correctly. Typically, the recommended application of pH minus is between four and 8.5 ounces per 10,000 gallons of water. If the water has a high pH balance (more than 7.4), you can use this chemical to get it back down to normal. Because this chemical is highly acidic, it should be handled with care and attention. It can create harmful reactions to the skin and eyes if it comes into direct contact with them, so gloves and goggles should be worn at all times. To keep the material in pristine condition, it should be stored in an airtight container.