How to Lower Calcium Hardness in Your Pool Drain and replace some water. Before you replace the water, test your water source. Use pool flocculant. If you can’t or don’t want to drain any water from the pool, try using pool floc to clump the excess calcium. Try muriatic acid. Click to see full answer. Considering this, how do I adjust the calcium hardness in my pool?The Calcium Hardness can be increased by the addition of Calcium Chloride. It is important to dissolve the Calcium Chloride in a bucket of water before adding to the pool. If you just pour it into the pool without pre-dissolving, it may form scale on the pool surface.Secondly, what causes high calcium in pools? A: In most cases, excess calcium happens when your pool water is not properly balanced. Common culprits are high pH, fluctuating temperatures, and evaporation. Also question is, what does calcium hardness do for a pool? Although soft water is desirable in everyday home use, calcium hardness is necessary in pool water. With sufficient levels of calcium dissolved, the aggressive nature of water is tamed and will help prevent the leaching out of certain substances in pool equipment.Does baking soda increase calcium hardness? Adjusting Hardness You can raise water’s calcium hardness easily by adding calcium chloride (CaCl2). Adding calcium chloride in the hours before or after treating with soda ash (sodium carbonate) or baking soda (sodium bicarbonate) will result in cloudy water.