How To Identify And Remove Pool Stains

Stains are one of the most irritating detriments to their investment that a pool owner can endure. To address this problem, the source of the stain must be identified, and the appropriate solution introduced as soon as possible.

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

Metal or rust-based - Metals can accidentally be introduced into pools from well water or corrosion from copper pipes.

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

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. We have provided more insights below.

GREEN AND BROWN STAINS - These stains are most likely organic stains caused by leaves or other plant matter.

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

BLUE, GREEN AND BLACK STAINS - 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 STAINS - This combination indicates iron as the culprit.

BROWN, BLACK AND PURPLE STAINS - 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.



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

For multiple 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 always to shock at dusk, or at night, for best results.

Once it’s 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.


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.


Preventing pool stains is as important, easy, and important as any other facet of pool maintenance.

To keep organic stains from forming, make sure to keep the correct level of sanitizer (i.e. chlorine) in the pool at all times.

Make sure pH and alkalinity are balanced, to keep the sanitizer working properly. 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 it 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 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.

Please see a list of other useful pool blogs here!

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 giving us a call on 1300 511 901 or contacting us if you are unsure. Mr Pool Man does not take any responsibility for incorrect dosages

Zodiac All In One Stain Remover 1KG - Iron RustPool Spa Chemical

Zodiac pH Down Tablets 2KG - Pool Acid Chemical Reducer

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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