Magnesium carbonate can form in swimming pool water as water scale, if the total hardness of the water is too high.
What is Magnesium Carbonate for swimming pools?
Magnesium carbonate is a white, solid, inorganic mineral salt. The amount of magnesium carbonate dissolved in swimming pool water is a factor in the total hardness level of swimming pool water, with calcium carbonate being the other major factor.
Excess of magnesium carbonate in a swimming pool can exceed the saturation point of the pool water. Any excess not dissolved can form water scale on the pool walls, floors, and at the water line. Although water scale formed by magnesium carbonate is softer and easier to remove than calcium carbonate, scale from calcium carbonate tends to form in much higher quantities than magnesium based water scale.