Water hardness levels should always be maintained between 200 to 400 ppm. Improper hardness levels can cause corrosion to your equipment and the spa surface. A primary indicator of low levels of hardness is foaming in the water. Liquid Calcium is simple to use and includes an especially high concentrate that adds convenience and savings. Example: to raise the hardness of 500 gallons of water just 20 ppm with Liquid Calcium requires only 3 oz verses 8 oz with almost all traditional competitor products. The most accurate measurement of water hardness is AquaChek Total Hardness Test Strips that provides readings between 0 to 1000 ppm. HT uses a high concentrate to save you money and add convenience because calcium increasers are limited to only allowing you to add a maximum of 3 oz at one time in hot water. After 3 oz you have to wait 30 minutes before adding more calcium increaser. A five minute treatment with HT becomes an afternoon event with most competitor products. RECOMMENDED USE Test your water with the use of AquaChek Total Hardness Test Strips. Add 1 oz per 7 ppm of increase required, not to exceed 3 oz if the water is warm. In cold water you can add up to 12 oz at one time. NOTE: There are no products on the market that will lower hardness levels. The only choices available are drain 12_ of your water and refill with soft water and retest results or call for delivered water making certain their water hardness levels are 400 ppm or less. If you have hard water make certain to use both Stain & Scale and Protections Plus along with keeping your ph in line. This will help prevent scaling.