Calcium Chloride

Water is "hard" when calcium is present in high levels. In-ground pools are susceptible to damage from calcium salts in the water. If the calcium levels are too low, water can leach the mineral from the pool walls, and damage the grout. Scale forms when the levels rise too high; the water clouds and metal fixtures might corrode. The correct level of calcium hardness i between s 150 and 200 ppm for concrete pools and 80 to 150 for vinyl-lined pools. To raise the level of low calcium by 10 ppm, add 15 gr calcium chloride per 1,000 litres (1 m3) of water. IMPORTANT: Dissolve the calcium chloride in a bucket of water first. Note:  Do not add more than 5 kg p 40 m3 of water at one time.  If the pool requires more than this, add the maximum amount then retest 12 hours later and make further adjustments.