Lowers pH to ideal levels in your spa or hot tub. Balanced water chemistry is the first, most important step to clean, sparkling water in your spa or hot tub. Generally pH levels above 7.6 cause cloudy water and eye irritation; and can reduce spa chlorine or spa bromine's effectiveness. Use spa down to lower the pH and alkalinity levels in your spa or hot tub water to the ideal recommended range of 7.2 to 7.6 ppm (parts per million).