GLB Alkalinity Increaser 15 lb Glb pool and spa products alkalinity up maintains proper alkalinity in swimming pool water to aid in preventing the pH level from changing Alkalinity up helps maintain proper water balance by keeping a proper alkalinity level of 80-120 When the pH value of the pool water fluctuates in short intervals, it is usually the result of a low total alkalinity condition of the pool water Alkalinity up will provide approx 10 parts per million increase in total alkalinity for each 10, 000 gallons of water Measures 11.4-inches length by 8.6-inches width by 6.9-inches height; works with chlorine, bromine, ozone, salt water pools, biguanide sanitizers