Natural Chemistry Spa pH Decreaser gently lowers the pH level of spas and hot tubs into the desired range, preventing many problems such as scale buildup, cloudy water conditions, and bather discomfort. Spa pH Decreaser uses all-natural sodium bisulfate to lower pH, avoiding the need for harsh chemical alternatives that can cause more problems than they solve. After use, your spa or hot tub water will be clean, clear, and healthy.