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Pool scale and surface stains can appear in almost any type of pool, including concrete, plaster or vinyl liner pools. Scale formation and staining are caused by the presence of excess minerals in your pool water.

Scale buildup is calcium carbonate that solidifies on pool walls and surfaces. It’s usually white or tan in color with a rough or gritty texture. Scale build up is caused by imbalanced water, particularly from having water with high Total Hardness, high pH and/or high Total Alkalinity.

On the other hand, staining or water discoloration can be a variety of colors, including black, yellow, or brownish. Pool owners commonly mistake stains or water discoloration for pool algae. However, unlike algae, pool stains do not brush off readily and are not slick or slimy.

Staining is often caused by the presence of excess minerals in your pool water that break apart into their metal components. Source water used to fill your pool, fertilizers, corrosion of copper pool equipment parts such as plumbing or heaters, and even some algae treatment remedies can introduce potential metal-related issues into your pool. Chlorine oxidizing products as well as other pH-altering products can react differently with metals, resulting in water discoloration or staining.

Follow these steps to remove and prevent scale formation and staining.

1

Test and Balance Water

Always begin by testing your pool water. Your test results will tell you if your water parameters are unbalanced. Pay special attention to your Total Hardness, pH and Total Alkalinity levels. Maintain Total Hardness between 175-275 ppm, pH between 7.2-7.6 and Total Alkalinity between 80-150 ppm. If needed, apply the appropriate balancers to restore balance.

2

Apply Scale and Stain Treatment

Scale formation and metal stains can occur together, therefore, apply a monthly preventative scale, metal and stain control treatment to protect equipment and remove fresh metal stains.

3

Brush Surfaces

Scale build up and stains can be stubborn to remove. Brush stained or scaled areas with a pumice stone daily for 5-7 days. Cleaning your pool regularly is an effective step to prevent common pool problems. Skim water surface to remove visible debris, brush walls, vacuum and empty skimmer baskets as part of your routine maintenance.

For best results, test and balance your pool water weekly. Download the Clorox® Pool app for expert water analysis and product and dosage recommendations. If your scale or staining problems persists, contact us for further troubleshooting.