HTH™ Spa pH Up helps balance pH levels in your spa water, improving both water quality and comfort. pH Up not only ensures that your sanitizer is working more efficiently, but it helps prevent corrosion of spa surfaces as well as significantly reduces skin and eye irritation. HTH™ Spa pH Up is great for all spa types including bromine, chlorine and biguanide.Use HTH™ Spa Test Strips to test your spa water. If pH measures below 7.2 ppm, add HTH™ Spa pH Up directly to the filter skimmer with the spa circulation system running. Refer to the on-pack chart for the correct dosage. After the spa circulation system has been running for 30 minutes, re-test pH and add more pH Up if necessary. Test and balance your spa water twice a week to maintain pH levels between 7.2 and 7.8 ppm.