PH Decreaser (Sodium Bisulfate) pH Decreaser commonly known as "Sodium Bisulfate" (Dry Powder), is used to lower pH levels in commercial and residential swimming pools and spas. This product is available in convenient 10, 25, & 50 lb. pails!  Why do you need to balance your pH levels? Controlling the pH level of your pool water is important not just for swimmer comfort, but also aids in the efficiency of chemicals and the life expectancy of pool mechanical and structural components. Many factors can influence the pH level. This includes debris, chemicals, and skin oils/waste brought into the pool by swimmers. (One of the many reasons you should shower before jumping into a pool!) Before checking or correcting the pH levels, check and correct the Total Alkalinity level. As the pH level of the human eye is 7.5, pool patrons often experience stinging eyes and discomfort when the pH levels are too far out of spec.  Instructions for use: 10 lb. of product per 120,000 may lower pH level by 0.2.