Natural Chemistry Spa pH Increaser boosts your spa or hot tubs pH level into the optimal 7.2 to 7.6 range, preventing corrosive damage to plumbing, equipment, and surfaces. Low pH can also cause skin and eye irritation for bathers. Spa pH Increaser uses all-natural sodium carbonate to steadily raise your spas pH level into the desired range, avoiding harsh chemicals that can cause more problems than they solve. Your spas pH is the critical factor in maintaining a proper water balance, which determines the health and comfort of your spa or hot tub.