Check the listing for details. Granular Calcium Hardness Increaser Plus For Swimming Pools - (Choose Quantity). Condition: New. Listed at 23.92 USD. Swimming Pool Granular Calcium Hardness Increaser (Plus) For Swimming Pools - (Choose Quantity Our Calcium Plus will raise your pool or spa water hardness level while preventing foaming and pool equipment corrosion. In some areas of the country, source water for pools has insufficient calcium hardness, which is needed to prevent corrosion of pool equipment and surfaces. Calcium Hardness Increaser effectively eliminates this problem and when used with other balancing chemicals, assures proper water balance. Just simply add our Calcium Hardness Increaser to your pool whenever the hardness level of your pool water drops below 150 ppm. Our Rx Clear® Calcium Booster also helps prevent corrosion of plaster finished, and metal equipment! Benefits: Increases water hardness The recommended range for pools is 200 - 400 ppm Helps prevent corrosion Suppresses foaming Compatible with chlorine, bromine, ozone, and biguanide sanitizers. Dosage Rate: Approximately 6 lbs per 10,000 gallons of water to raise hardness level by 50 ppm Spread the product over the surface of the water while the pump is running. Do not pre-dissolve this product. Features: CALCIUM PLUS - Use Swimming Pool Calcium Booster when the calcium hardness reading in your pool drops below 150 ppm. Raising calcium hardness helps prevent the corrosion of metal and plaster surfaces. Also helps prevent the foaming of certain chemicals. BE AWARE - Do not add this product on the same day that either pH plus or alkalinity increaser has been added to the pool water. Add when water hardness levels drop below 150 ppm. Spread the product over the surface of the water while the pump is running. Do not pre-dissolve this product. PREVENTS CORROSION - Rx Clear® Calcium Plus helps stop corrosion of metal surfaces such as light fixtures, railings, ladders, screws, pool cover components, pool heater components, and metals in your pump or filter. Also prevents etching, pitting, and delamination of concrete, plaster, gunite, shotcrete, and fiberglass pools WATER CHEMISTRY - One of the most important aspects of proper swimming pool care involves the maintenance of balanced water chemistry. When swimming pool chemicals are not at their ideal levels, swimmers can be at risk of contracting illnesses and suffering from skin irritation, the water can turn dull and cloudy, and pool or spa equipment, hoses, and surfaces can become damaged. DOSAGE - The ideal range is 200 to 400 parts per million (ppm). Six lbs. per 10,000 gallons will raise the hardness level by approximately 50 ppm. The minimum calcium hardness level is 150 ppm. Trust Rx Clear® as the most reliable leader in pool cleaner products and supplies.