Rendezvous Alkalinity Up - 1 Lb Rendezvous Alkalinity Up - 1lb Bottle Rendezvous Alkalinity Up granular additive raises spa water alkalinity and helps maintain pH levels Sanitizers work most efficiently when pH is kept in proper range Keeping your spa balanced is an important step in getting the most out of and preserving the life of your spa spa, hot tub or jacuzzi compatible with chlorine, bromine, ozone, and biguanide sanitizers