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Manganese Stain Treat
1lb per 10,000 gallons
Discovering dark purple or black stains in your pristine pool can be discouraging, but you do not need to drain your water to fix it. These unsightly marks are typically caused by oxidized manganese—a common mineral often found in well water—but they are not permanent. In this how-to, we show you how you can remove them fast as well as how to prevent them in the future.
Steps
minute(s)
Turn off your pump system and bypass the timer.
Lower the chlorine level to below one (1) ppm – the lower the better – by either abstaining from adding chlorine or using a chlorine neutralizer, such as No Mor Chlor™ or an equivalent product.
Lower the pH to 7.2 and the Total Alkalinity to 80 ppm or below by using a pH decreaser and Alkalinity decreaser, such as No Mor Muriatic Acid™ or a conventional liquid acid. If you need to lower only the alkalinity, you can use Easy Alkalinity Down™ or an equivalent dry acid.
Add 1 lb of Manganese Stain Treat™ per 10,000 gallons.
For pools where color fastness is a concern, or for areas with widespread staining, dissolve Manganese Stain Treat™ in a clean bucket of water before pouring it evenly around the perimeter of the pool. Some clouding is normal and will subside in 24 hours.
Wait 12-24 hours for results. Repeat the application until all stains have been removed.
Raise the pH using Easy pH Up™ or Sodium Bicarbonate (Baking Soda).
Soda Ash is not recommended, as it may lead to stains returning.
Raise the chlorine reading slowly, avoiding increases of more than 5 ppm per dose per day. Larger doses may cause staining to reform.
Use a stain preventative such as No Mor Stains & Scale™ weekly to keep the pool free of stains.
Manganese typically enters swimming pools through source water, most commonly from private wells, though it can also be introduced by fertilizers or trace amounts in municipal water supplies. Initially, this mineral is often dissolved and invisible to the naked eye. However, when you add a sanitizer like chlorine, the manganese oxidizes. This chemical reaction causes the metal to precipitate—or “fall out”—of the water, leaving behind stubborn purple, black, or dark gray stains on your pool’s surface and grouting.
Removing an iron stain is a lesson in chemistry. Since the stain was formed by oxidation (adding oxygen to solidifies the metal), removing it requires the opposite process: reduction.
Products like Manganese Stain Treat™ utilize reducing agents to strip the oxygen from the oxidized manganese. This chemical reaction converts the solid, visible stain back into a dissolved, invisible form that can be suspended in the water.
Once the manganese is lifted from the surface and dissolved, it is crucial to use a sequestering agent. This “locks up” the metal, preventing it from re-oxidizing and staining the surface again. It is a simple, direct, and guaranteed way to restore your pool’s sparkle.
