How To Identify And Remove Pool Stains

Pool stains are one of the most irritating maintenance issues a pool owner can face. To address this problem, the source of the stain must be identified and the appropriate solution introduced as soon as possible. If you’re having issues with staining in your pool, check out our guide on how to identify and remove pool stains below.

How to identify and remove the two main types of pool stains

Metal or Rust-Based Stains

Metals can accidentally be introduced into pools from well water or as a result of the corrosion of copper pipes.

Organic Pool Stains

Leaves, berries and other organic debris can also leave stains if allowed to settle on pool surfaces.

Stain Colour Identification

The best way to distinguish metal from organic stains is by colour. Different colour combinations provide good indicators of exactly what substance is causing a given stain. Read on to find out more:

Stain Colour Possible Source

Green and Brown

These stains are most likely organic stains caused by leaves or other types of plant matter.

Red and Blue

These stains are more than likely from brightly coloured berries; check the area around the pool for the offending bush.

Blue, Green, and Black

When a stain is a mixture of dark blue, green and black, and there is no evidence of organic matter, it is likely to have been caused by copper.

Green, Brown, and Red

This combination indicates iron is the culprit.

Brown, Black, and Purple

This dark colour combination is caused by manganese.

Once you’ve got a good idea of the cause of a stain, it’s time to test the theory and confirm the source of the problem. If an organic stain is suspected, try applying a small amount of chlorine directly to it. An organic stain will come away easily. Metal stains, on the other hand, react best to ascorbic acid, the kind found in citrus juices. The best method is to apply crushed vitamin C tablets to the stain and see if it is removed or lightens.

How Do You Get Rid Of Pool Stains?

Now that you have a basic idea of how to identify the different types of pool stains, it's now time to dive into how to get rid of them foor good.

Organic Pool Stains

Chlorine: Your best friend against organic pool stains

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Organic stains are best addressed by super chlorinating the water, then brushing. First, test the water to ensure the balances of pH and alkalinity – the pH should be between 7.4 and 7.6, while alkalinity should be between 100 and 150 ppm (parts per million). Use test strips to test the water.

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For multiple stains or large stains, the water should be triple shocked by adding 3 pounds of calcium hypochlorite pool shock for every 40,000L of water. Remember to always shock at dusk or at night for best results.

Once the pool water has been shocked, thoroughly brush all the stains, then let the pool circulate for at least eight hours. Continue to brush the stains intermittently and keep the chlorine level high until the stains are finally gone.

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Metal Pool Stains

Metal stains usually require professional intervention. The first step is to take a water sample to your local pool care retailer to determine exactly what kinds and levels of metals are plaguing your pool. After that, the professional can recommend a special additive designed to remove metal stains.

Add the chemicals according to the manufacturer’s instructions, brushing the stain to help the process along. Should the additives and brushing not do the trick, you may have to use a targeted citrus-based stain remover, also available at pool care retailers, to attack the stain directly.

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Future Stain Prevention

Preventing pool stains is as easy and important as any other facet of pool maintenance. To keep organic stains from forming, make sure to keep the correct level of sanitiser (i.e. chlorine) in the pool at all times. Make sure that both the pH and alkalinity levels are balanced, to keep the sanitiser working properly.

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Keep your pool clean by regularly vacuuming (manually or with an automatic pool cleaner) and skimming the surface of the water.

The best preventative measure against metal stains is to test water regularly for the presence of metals and address any issues before stains form. If your pool is prone to metal contamination due to well water or other factors, be sure to use a stain and scale product as part of regular pool maintenance. These products sequester minerals in a solution, preventing them from binding to pool surfaces.

In the case of a copper problem, it’s worth noting that low pH can also cause a recurrence of stains. Low pH indicates acidic water, which corrodes copper and introduces it into your pool. Adjust pH levels accordingly.

And finally, always keep complete set of pool chemicals so you can act on any stain problem as soon as possible. Stains (especially organic stains) can multiply exponentially at night. So at the first sign of staining, treat it immediately. This will save you from extensive pool shocking and scrubbing down the line.

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Products Featured in this Blog Post

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Note: This blog is a rough indication of advice for an average sized pool and average dosing recommendations. Mr Pool Man always recommends getting your water tested by a pool professional before adding any type of chemicals for your own safety, or contacting us if you are unsure. Mr Pool Man does not take any responsibility for incorrect dosages.

Do you have any questions about this topic or the featured products? No worries, we're here to help! Drop us a question down below and we'll get back to you ASAP.

Happy swimming :)

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Post author:

Tom Hintze

Head of eCommerce & Operations at Mr Pool Man,
Co-Founder at Water TechniX

1 comment

  • Hi Tom
    Hope you can help with stain on our bullnose-coping
    Would like to send you a picture
    Thank You

    Annette on

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