ProTeam Spa Calcium Up is an easy and effective way for spa owners to boost their calcium hardness level, preventing costly damage to spa plumbing, surfaces and equipment. If your calcium hardness level is too low, your water will become corrosive, attacking your spa to try to bring itself into balance. Its granular formula quickly raises your calcium hardness level up to 30 ppm with each dose, allowing you to easily reach the optimal 150-300 ppm range. This will not only protect your pool, but will give bathers much more comfortable water. Best of all, Spa Calcium Up is made right here in the USA, allowing you to buy with confidence.