Dealing with Scaling and Staining


Unsightly scale build-up or staining can ruin an otherwise good-looking pool. Scaling occurs when calcium deposits are left on pool surfaces after water has evaporated. This develops a line of white or grey scale around the edge of your pool that can be difficult to remove. Scaling can also be seen when calcium deposits come out of suspension and can be seen floating in the pool.

Staining can be caused by a chemical imbalance reacting with the pool surface and can be various colors.

There are two types of scale that pool owners have to face.

Calcium Carbonate – This type of scale is white, flaky, and relatively easy to remove using a pumice stone, Stain Eraser, acid washing, or Leslie’s Ultimate Scale and Stain Remover. These products will be discussed below. To determine if the scale you have is calcium carbonate, apply a small amount of muriatic acid on the scale. If it bubbles or foams at contact, then you know you are dealing with calcium carbonate.

Calcium Silicate – Calcium silicate is greyish-white, and is much harder to remove than calcium carbonate because the scale will have been present for much longer. To see if the scale you have is calcium silicate, use the same method as above. The only difference will be how the scale and acid react to one another. Unlike calcium carbonate, calcium silicate will have little to no reaction to muriatic acid. Unfortunately, the only way to effectively remove this type of scale is to use a pumice stone and hard work, or call a professional to help you.

Scale Removal Products

Pumice Stone – A pumice stone is a coarse stone that can be used on ceramic tile or concrete surfaces to rub away both types of scale. It is very effective, but wears quickly. When using a pumice stone, make sure to keep both the stone and the surface you are cleaning wet at all times to prevent scratching.

Stain Erasers – A stain eraser not only works on stains, but on calcium carbonate as well. It can also be attached to a tele-pole for convenient use. There are also multiple Stain Erasers available that will work on different surfaces.

Leslie’s Ultimate Scale and Stain Remover – This chemical, which is safe for all surfaces, is added to the water to slowly wear away the stains and re-suspend the calcium carbonate. Over time, you may see results on calcium silicate, but it is not recommended. Scale and Stain is applied by adding 16oz per 10,000 gallons of water to a bucket of pool water. That newly mixed water is then broadcast into the pool. Maintenance doses may be applied every two weeks.

Applications of Ultimate Scale and Stain Remover can also help prevent calcium coming out of suspension in your water. This problem is caused by an imbalance in your pH and Total Alkalinity. Properly maintaining these levels can help prevent this problem in the future. However, once the calcium is out of suspension, the only way to actually remove it is to allow your filter to take it out of the water.

If you have any questions about removing or preventing stain and scale, contact a local Leslie’s professional or visit