Decreases the pH level when your hot tub water tests as alkaline. The recommended range is 7.4 - 7.8 ppm. In this range, both the spa user and equipment are protected. If the pH levels are not in the acceptable range use pH Up to make the water more basic or pH Down to make the water more acidic. Note: Spa Sauna Direct only ships pool and hot tub chemicals within the continental United States.