How to Remove Iron Stains from Swimming Pools

Iron is the most common type of metal/mineral staining in pools. So odds are good you'll run into brown rust stains in your pool. In this how-to, we show you how you can remove them fast as well as how to prevent them in the future.

At a Glance







Lower chlorine to 1.0 ppm

Lower your chlorine reading to less than 1.0 ppm by either using chlorine neutralizer or abstaining from adding your sanitizer for a few days.


Lower Total Alkalinity (Optional)

Lower your Total Alkalinity by using one (1) bottle of No Mor Muriatic Acid™ per 20,000 gallons. You can add more as necessary. You can also use regular liquid muriatic acid.


Add Pool Stain Treat®

Add one (1) bottle of Pool Stain Treat® per 20,000 gallons of pool water.



After 5-10 minutes brush the walls of the pool. One good brush over the wall should be fine. 

What You’ll Need

  • Pool Stain Treat®
  • No Mor Muriatic Acid™
  • Chlorine Neutralizer (sodium thiosulfate) (Optional)
  • Brush Attachment

Extra Tips

  • For colored plaster, painted fiberglass, exposed aggregate pools you will need to dissolve Pool Stain Treat® in a bucket of water first before pouring it into the swimming pool to prevent discoloration.
  • For widespread staining, dissolve Pool Stain Treat® in a bucket of water and pour around the pool. This will help give an even finish.
  • If your pH is above 7.2, you can go ahead and let your system run. Otherwise, turn off your pump until your raise your pH to at least 7.2.
  • Lower your Total Alkalinity relative to your water hardness according to the Hamilton Index™
  • Avoid shocking more than necessary. Shocking can lead to metals dropping out of the water and staining.
  • When using a non-liquid balancing chemical (such as pH increaser or granular acid), dissolve it first and pour it around the pool. This will minimize chances of metal staining.
  • Consider using a preventative stain treatment such as Pool Stain Treat® to keep stains from returning.

Still need help?

Still have questions? Need an expert’s advice? Visit our support center for additional documentation and to open a ticket with a Pool Technician.

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