Scale build-up is usually white or tan in colour and feels like sandpaper in the early stages. As it gets worse, the edges become sharp, and if on the bottom, can actually cut people’s feet. Scale is calcium carbonate that has come out of solution and solidified on walls. It is caused by poor water balance parameters, such as high calcium hardness, high pH, or high total alkalinity over a period of time.
Scale build-up can be as hard as cement and is almost impossible to remove by chemical additions to the pool. If the scale is fairly new, you can try adding 250 mL of Scale Inhibitor or Salt Pool Stain & Scale Control per 10,000 litres and brush daily for one week. This may aid in loosening the scale so that the filter can remove it.
Most of the time, the deposit must be physically removed, and usually requires draining. Acid washing or sand blasting will remove it from pool surfaces other than vinyl. Vinyl liners must be replaced.
To prevent scale build-up, maintain proper water balance. If the total hardness of the fill water is high, add 125 grams of Scale Inhibitor or Salt Pool Stain & Scale Control per 10,000 litres monthly.