HT pH/Alkalinity Down lowers both pH and Alkalinity. With the use of spa test strips make certain to maintain your alkalinity between 80 to 150 ppm and your pH between 7.2 to 7.8 ppm. Important to use whenever pH climbs above 7.8 ppm! RECOMMENDED USE 1. Turn OFF all pumps and blowers 2. Add _ oz (1 _ tsp) for every 500 gallons NOTE: For best results add granular to small bucket of water then pour into spa 3. Turn on filtration pump for 30 minutes 4. Test and repeat procedure is pH is above 7.8 ppm