Pool Stains: ​​Great Tips on Identifying and Eliminating Them

Are you having trouble identifying or removing pool stains? Learn how to identify pool stains, what causes them, and how to remove them for good.

One of the biggest nuisances in a pool is stains. They can be challenging to remove, especially when they’ve been sitting there for a while.

Luckily, in this article, we share some tips on identifying and eliminating them, so your pool always looks its best.

What Causes Pool Stains?

Cloudy and Green Water in Swimming Pool

Several reasons can cause common pool stains. Factors inside your pool often cause stains, and external factors also play a major role. The most common examples fall into these two categories:

Organic: This includes algae growth, plant matter, and bird droppings.

Inorganic: This includes rust, metals, minerals, and pool chemicals. You can usually remove inorganic stains more easily because it’s more soluble than organic stains. 

Once you’ve determined the sort of stain, you may choose the appropriate pool stain remover. The easiest approach to determine this is to examine the stain’s color. 

Greenish-Brown Stains: There are many possible causes, including decaying leaves or other plant matter.

Reddish-Blue Stains: These are almost certainly from brilliantly colored berries. If you have fruit-bearing trees or bushes near your backyard oasis, this could be the cause.

Blueish-Greenish-Black Stains: Organic debris such as leaves or berries might be the source of this staining. However, if there’s nothing like that surrounding your pool, they were probably caused by copper, which is present in well water. Also, if you have copper piping anywhere in your plumbing system, it may have been eroded, resulting in pool stains.

Greenish-Brownish-Red Stains: This combination of colors indicates the presence of iron stains. Or perhaps there’s a source of iron in your area, which includes metal fences and other metal pool accessories. Rain could wash away rusts to your pool which leads to greenish-brownish-red colored stains.

Brownish-Blackish-Purple Stains: This darkish color combination is due to Manganese. This naturally occurring metal is present in well water and local water sources. Residential water is treated to decrease Manganese, but it’s not entirely removed.

How to Determine the Stain’s Cause?

Once you’ve determined what caused the pool stains, you’ll need to test your theory and determine the root of the problem.

Organic Stain Test: Applying a little quantity of chlorine straight to the stain may help remove an organic stain. If it is an organic stain, it should be easy to get rid of.

Metal Stain Test: Metals are not affected by chlorine in any significant way. That’s why certain pool accessories, like pool ladders, are made of metal.

Steps to Remove Organic Pool Stains

Pool Maintenance Tools and Stain Remover

Organic pool stains are very easy to remove and do not pose a significant danger to your pool’s integrity. Because natural factors cause these smudges, you may follow the methods below to eliminate any unattractive organic pool stains.

Step 1: Use a Pool Net to Remove Debris and Leaves From the Surface of the Pool

Use a pool net to remove any debris, twigs, plants, leaves, and other trash which could be in the pool.

Step 2: Check the Water’s Chemistry Levels

Reduce your chlorine levels to less than 1.0 ppm. To do this, you can either use a chlorine neutralizer or stop adding any type of sanitizer for a few days.

Step 3: Shock the Pool

Water with chlorine and powerful shock treatment (ozone and oxidizers) can help remove organic stains immediately. Chemical treatments like shock and ozonation will also remove inorganic pool stains. 

Pool Pro Tip: “Shock your pool at night to enable the chlorine to do its job of disinfecting the water. Chlorine will dissolve if you shock your pool during the day because of the ultraviolet radiation from the sun.” - Matt Giovanisci, founder of Swim University®

Step 4: Brush the Stains Relentlessly

After shocking the pool, brush away any specific areas on the pool’s floor or wall

Step 5: Run the Pump of Your Pool

Now is the time to turn on your pool pump and begin filtering your water.

Step 6: Keep Brushing the Stains

There is always a possibility that some stains will remain. So you may need to perform a second round of brushing to ensure they entirely disappear.

Step 7: Double-Check to See if the Stain Is Still Present or Has Gone

After you’ve done all the steps outlined above, check to see if all of your hard work has been fruitful. If the stain is still there, simply repeat the process until all stains have been removed.

Steps to Remove Metal Stains in Your Pool

Cleaning Pool and Removing Stains Equipment

Many pool owners may be concerned that metal stains may become a permanent addition to their pool. Fortunately, they can remove even the most stubborn smudges by following these steps:

Step 1: Lower the Chlorine Concentrations in Your Water

While chlorine helps remove algae, too much could add to your pool staining problems. Chlorine oxidizes some portions of your swimming pool, like the bottom, so you should lower the chlorine levels to 0 ppm. To do this, you can drain a partial amount of your pool’s water and add fresh water. You may also buy a chlorine neutralizer, which will allow you to reduce the chlorine levels fast.

Step 2: Apply Algaecide

If you want to avoid metal stains, you’ll need to remove the algae first. Algae is the base of most stains because it’s what can be found on the bottom of your pool. You can apply an algaecide to kill the algae quickly and effectively. 

Step 3: Add Vitamin C to the Stain

Vitamin C is an antioxidant, which means it can prevent the oxidation of metals. It can also work as a powerful oxidizer and help remove stains. Use a half-pound of ascorbic acid for every 10,000 gallons of pool water.

Step 4: Apply Ascorbic Acid for Larger Stains

Some bigger metal pool stains need extra effort, so try spreading ascorbic acid evenly on the pool’s surface. For every 10,000 gallons of pool water, use a half-pound of ascorbic acid.

Step 5: Circulate the Pool’s Water

Then, turn on the pool pump to let the stain-eliminating pool chemicals circulate throughout the pool via the filters. 

Step 6: Check for Any Remaining Stains

It’s now time to find out if all of your hard work was worth it! Repeat steps 3-5 as necessary until the metal pool stains are no longer visible. 

How to Prevent Stains in the Future?

Pool Net Skimming for Leaves

Swimming pool stains can be ugly to look at, but there are ways you can prevent them from happening in the future.

To avoid organic stains in your pool, do everything possible to maintain it clean. This may include the following:

  • Skimming the pool’s surface to prevent leaves, twigs, and other organic waste from falling to the bottom of the pool and accumulating there and causing staining.
  • If you’ve got trees and bushes surrounding your pool, make sure to start trimming if they become too overgrown.
  • Save and invest in a pool cover or a robotic pool cleaner.

Preventing metal stains in your pool includes the following:

  • Using a good water chemical test kit to keep the pool water balanced (particularly the alkalinity, pH, and sanitizer levels);
  • Keeping your pool plumbing clean and efficient
  • Maintaining the pH level in your pool at optimal levels


We hope these tips have helped you clean and prevent staining issues. If you have any other queries or comments, feel free to leave them below.

For more great pool articles, check out our website. Swimming pools are not as difficult to maintain as you might think. Here are a few guides to help you. Keep your pool clean and safe. Thanks for reading!

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About the author

Brian Anderson

The rather dry pool world out there is in need of some passion to make it shine. With the help of my son Ruben and his wife Maria our mission is to help you create the favorite spot of your house - your pool.

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