For use in your hot tub or swim spa, EzCal Hardness Increaser raises the amount of dissolved calcium in the water. Very soft water can cause etching to occur resulting in the surface of the tub becoming abrasive and uncomfortable for bathers. Rough surfaces can also encourage algae growth. Fully soluble in water, and does not affect the pH or total alkalinity levels.
Easy to use. Full usage instructions on the side of the product.