Measure the pH of the spa water using test strips or a test kit.
Refer to table on packaging to determine the correct dosage
Add hth spa pH Decreaser to the filter skimmer with the spa circulation system running.
Leave running for 30 minutes and recheck pH.
Add additional hth spa pH Decreaser if required.
Add only to spa or hot tub water. DO NOT mix with other chemicals, including other hth spa products.