It’s frustrating to find stains in your pool after spending hours each week on maintenance. Be assured, though, that stains are inevitable, no matter how careful you are with your pool maintenance routine. So, if you notice stains on the walls of the pool, on the steps in the shallow end, or anywhere else in the pool, be assured it isn’t a reflection of your efforts.

The key to ridding the pool of any stain is to first identify what it is. Sounds simple, but it takes some detective work on your part to tackle this step and move on to removing the stain. 

This article will show you how to identify pool stains, learn what is causing them in your pool, and provide some tips on how to prevent them from coming back. 


The Most Common Pool Stain Causes

Many commonplace things found near or in your pool can cause a stain, like leaves, dirt, minerals, and bodily oils. To identify the cause so you can attack the problem, let’s look at the two main categories of pool stains:

Organic Stains

Leaves, dirt, landscaping material, berries, grass, bugs, worms, and other organic materials can leave stains if left too long in the water or on the surfaces of the pool.


Metal Stains 

It’s strange to think about metals finding their way into your pool, but several types of metal can accidentally get into your pool in increase the level of TDS. If your primary source of water is a well, heavy metals like arsenic, antimony, cadmium, chromium, copper, lead, and selenium can get into the water through groundwater movement. Another source of metals is from corroded copper pipes. Metal pool accessories, parts, and equipment that have become rusted can also cause stains.

This information helps, but how do you know which is the cause, organic materials or metals?


Identifying Pool Stains


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A stain’s color is the key to what type it is. Once you learn which color to match to what type, as well as a few color combinations, you can diagnose your pool stains faster.

Here are the color descriptions you need:

– Green or greenish-brown stains: Organic

Usually caused by leaves, twigs, algae, or other plant life. Sometimes caused by bugs or other critters that fall into the pool.

– Red or blue stains: Organic

Berries from bushes near the pool leave bright red or blue stains. 

– Blue-green or teal stains: Metals

Copper often leaves this color combination.

– Dark red or brown stains: Metals

Iron results in these dark wine-colored stains.

– Black or purple-ish stains: Metals

This color is usually produced by manganese.

These color combinations identify whether the stains are caused by organic matter or some kind of metal in the water. The next step is knowing how to get rid of them.


How To Remove Pool Stains

Here are some basic tips for removing both organic and metal stains in your swimming pool:

Removing Organic Stains

Organic stains, like those caused by leaves or algae, are the easiest to remove. You may have to scrub but they are responsive to treatment.

Try this:

– Balance your pool’s pH and alkalinity levels first.

– Shock the pool later in the day.

– Use granular chlorine on the stain.

– Let it absorb.

– Scrub the area with a brush or grout scrubber.

– If the stain persists, use an enzyme treatment.


Removing Metal Stains

Metal stains don’t respond well to chlorine and each metal requires a different attack. Let’s break down the methods for a few specific metal-based stains:

Iron-Based Stains

Ascorbic acid usually works well on iron-based stains: 

– Dilute the ascorbic acid in water.

– Scrub.

– You can sprinkle some directly onto the spots, too. Scrub.

– Run the pool filter for an hour.

– Repeat the above until the stain is gone.

– Add a metal eliminator to the skimmer basket as a way of preventing future stains.


Copper-Based Stains

Copper pool stains respond better to citric acid. Follow the same steps as listed above, but use citric acid.

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Rust Stains

The methods for the previously-mentioned stains from organic or metals often work well on rust, too. But there is a faster method you can utilize:

– Fill a sock with dry acid and place it over the rust stain.

– Wait for a few minutes and check the stain. 

– You can also scrub the stain with either ascorbic or citric acid.

– Remove the sock as soon as the stain is gone so no discoloration is left behind.

– This also works if you’re trying to get rust stains off the bottom of the pool. Simply apply the dry acid sock to the stain with a telescopic pole.

Next, we will talk about some other common stains pool owners often have to deal with. 


Waterline Pool Stains

Look at your pool’s water line. If you see a pinkish-white residue, it’s caused by organic matter building up over time. To remove these stains:

– Add an enzyme treatment to your pool.

– Brush the stains with sprinkles of granular chlorine.

– Use a brush or pool stain eraser for hard stains.


Mineral Pool Stains

Mineral stains look like scaly white chalk and form deposits on the pool right above the water line. The water will often also be a little cloudy if this staining is present. The cause is excess calcium in the water.

To remove these stains:

– Mix half and half vinegar and water and use it to scrub the stain.

– You can also use a soda and vinegar mixture.

– Or even simply lime juice and salt can be effective.


Effectively Preventing Stains in Your Pool

To keep stains to a minimum in your pool, there are some specific tips you can follow:

– Test the water regularly

– Keep your pump pipe fittings in good repair

– Maintain your pool’s chemical balance 

– Use sequestrants and chelators to halt stains

– Run the pump/filter for at least eight hours a day (a pool pump timer is great to help ensure this happens!)

Cover your pool when it’s not in use


Identifying, Removing, and Prevnting Pool Stains is a Team Effort

Stains on a swimming pool are inevitable. Most stains are caused by organic matter or residue from metals that find their way into the pool water. The color of a stain will identify its cause and then you can use the appropriate products and methods to eliminate them. Although some staining is unavoidable, the best way to keep stains to a minimum is to clean and maintain your pool regularly.

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Here at Pool School Videos, we’ll show you how to prevent and eliminate stains in your pool. You can’t beat the professional knowledge you get through Pool School Videos, which comes with exact, step-by-step instructions in 20 in-depth self-paced videos. We’ll help you become a pro at dealing with stains and properly maintaining your pool while saving money doing it. These videos provide information not found anywhere else and they are all available now for an affordable one-time fee.

Pool School Videos was created by pool professional Mike Steele, aka “The Pool Doctor.”  Mike has over 30 years of experience in professional swimming pool maintenance and his goal is to make pool care as simple and effective as possible. After you buy the video series, you will also become a member of our private Facebook group that provides personalized guidance. Simply post your pool-related questions and Mike will answer them within 24 hours. 

Get started today and save hundreds of dollars on pool care each year with the help of Pool School Videos!