Pool Stains & Scale: How to Fix Them

Pool Stains & Scale:  How to Fix Them

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The Problem

Iron, copper and manganese can cause green, brown and purple stains on pool surfaces. Leaves, sticks and other organic debris can cause brown stains on pool surfaces. If the stains are ignored, they may become impossible to remove.

Recommended solutions

  • Take action as soon as the stains are noticed.
  • Ensure water is properly balanced. Lower pH to 7.2-7.4.
  • Brush the stained areas daily for at least 5-7 minutes using an 18" curved wall brush.
  • Use hth® metal & stain defense according to label directions.
  • Organic stains will slowly disappear with the regular use of chlorine sanitizer and shock products.
  • Brush the stained areas to help remove the stain.


The Problem

Higher levels of calcium combined with high pH and/or high Total Alkalinity (TA) can cause scale buildup on pool surfaces. Scale is noted by the off-white, gray or tan color, rough texture and release of chalky dust when brushed.

Recommended solutions

  • Check and adjust water balance. Adjust pH to the lower end of the range (7.2-7.4).
  • Use hth® metal & stain defense according to label directions.
  • Brush the scale areas at least daily. More frequent brushing will help speed up the removal of the scale.
  • If softer water is available, the Calcium Hardness (CH) level can be reduced by draining some of the water in the pool and replacing it with softer water.

    Preventative maintenance

    • Maintain water balance parameters at all times.
    • If the fill water already has high hardness, keep the pH and Total Alkalinity (TA) in the lower half of their respective ranges.
    • Add hth® metal & stain defense weekly.

    As always, we’re here to help. If you have questions, contact our help line at 1-866-HTH-POOL or talk to our experts with our live chat!


    Please read the following important reminders before adding pool chemicals to water:

    • NEVER mix products together or dissolve before use.

    • ONLY enter pool when FAC levels are below 4 ppm to prevent risk of bodily harm.