What is it?

Scale formation is created when there is an oversaturation of minerals in the pool water and water conditions do not allow them to remain dissolved or soluble. Those conditions may be high calcium hardness, high temperatures and/or high pH. The minerals drop out of solution and attach to pool walls and equipment and can damage them if the scale is not removed. Saline (salt) chlorinators are especially susceptible to scale build-up due to the intense water conditions within the cell itself.