How to Remove and Prevent Metal Stains In Your Pool

Written by Michael Dean
February 28, 2024

man removing metal stains from swimming pool

Staining can be a big issue for pool owners, and depending on the type of stain you are dealing with, they can be pretty hard to get rid of. Metal stains in your pool can be notoriously difficult to remove. But if you are dealing with this, don’t panic! The good thing is that it is totally possible to eliminate and even prevent metal stains in your swimming pool, however pesky they can be. 

In this post, I will walk you through the process of removing metal stains in your pool and give you some tips on how to prevent them from occurring. 

Main Takeaways

  • I recommend using a chelator to remove fresh stains and prevent further strainings caused by metals.
  • Ascorbic acid or crushed-up vitamin C applied directly on a metal stain can also lift it from the pool’s surface.
  • Test your water for the presence of metals regularly, at least once per week.

Step-by-Step Process: How to Remove Metal Stains in Your Pool

If you have noticed metal stains popping up in your swimming pool, you should be vigilant and work to remove them as soon as possible. Here is my step-by-step walkthrough for removing metal stains in your pool.

Step One: Identify the Stain

Identifying which metal has caused what stain is the first step to solving the problem. Different metals can cause different types of stains. And your ideal removal method will be different depending on the type of stain. For instance, copper causes greenish stains, while iron can cause brown or reddish ones.

Step Two: Test the Water

The next step is testing the water to determine the current composition of chemicals and metals in the pool. If your pool chemicals are out of whack, the entire chemical ecosystem can be thrown off. You should test your pool water regularly using a liquid testing kit or taking a water sample to your local pool store. Ensure that all of your pool chemicals are within the ideal range and adjust them as necessary.

Step Three: Add a Chelator

A chelator acts as a magnet that attracts and bonds with the ions of any metal ions present in the pool—this prevents the metals from being oxidized and, as a result, prevents them from staining the pool surface. A chelator will remove fresh stains and prevent further strainings caused by metals. Apply a minimum of 1 and a maximum of 3 quarts of any chelator to the pool per 10,000 gallons for every 1 ppm of metals and run the pool filter for the next 8 hours to allow the chelator to work.

Step Four: Brush and Buff

Once the chelator has had time to get to work, use a soft pool brush to get started with some gentle scrubbing. On stained areas, sprinkle some ascorbic acid or crushed-up vitamin C on the stain, then move the brush in circular motions.

Step Five: Run the Pool Filter

Once you have successfully cleaned off the metal stains, run the filter for 24 hours until the water runs clean. If the stains haven’t faded completely, repeat steps 3 to 5.

If you want a video walkthrough, check out this video from my friend Craig Wooster. He explains the metal stain removal process very clearly.

For a detailed breakdown of getting rid of pool stains, check out my article on the topic.

Is It an Organic Stain or a Metal Stain?

Some organic stains can look pretty similar to metal stains, so it is important to know how to distinguish metal vs. organic staining. Here are a few ways you can identify the nature of the stain.

Color and Texture

If the color of the stains in your pool looks greenish, brownish, or black, they could be algae. In addition, the texture of an organic stain might be soft and slimy.

In contrast, the color of a metal stain might be more dark or reddish brown, blueish-black, or greenish-black, depending on whether it originates from iron, copper, or manganese. The texture will also be flat or rough, depending on the nature of the staining.

Response to Vitamin C

Vitamin C is a great way to get rid of metallic stains, so if the stain responds to ascorbic acid, it is not likely organic. Place a vitamin C tablet on the stain and let it sit for at least 5 minutes.

If you find that the stain is unaffected by the vitamin C, it is probably organic. However, on the other hand, if the vitamin C managed to lighten or entirely remove the stain, it’s most likely a metal stain.

Response to Chlorine Granules

While ascorbic acid works wonders for metal stains, chlorine is the main method for getting rid of organic stains. So, sprinkle some granular chlorine directly on the stain, scrub the granules into the stain with a brush, and then let it sit for 10 to 15 minutes.

If you find that the stain is lightened or removed by the chlorine, it is most likely organic.

On the flip side, if you find that the stain has been unaffected by the chlorine, it’s most likely a metal stain.

Test for Metals

Another useful way to establish whether the stains on your pool surface are metal is to test your pool water for metal content using a home test kit designed specifically for metals. Plus, high levels of specific metals will even be able to indicate what type of metal is causing the stain (e.g., high iron content in the water would mean a potential iron stain).

Types of Metal Stains

There are a few different types of metal stains you could be dealing with in your pool.

Copper Stains

Copper stains in the pool range from a light green to turquoise discoloration and can be spotted near the pool walls and surfaces near the pipes. They are caused by an excess of copper in the water, which can occur due to corroded pipes or heat exchangers or even too much algaecide. If your pool has a high copper content, it can also cause the water to turn green.

Photo: CPO Class

Iron Stains

These metal stains are brown, reddish-brown, or orange in appearance. Iron stains are streaks and are typically concentrated in and around areas near metal objects. Iron can find its way into your pool through rusting pool equipment, well water, or via fertilizers.

Photo: Swimm Solutions

Manganese Stains 

Manganese stains are often purple or black, appearing in splotches or streaks. Manganese can creep into your water through the local municipal water supply or via well water since these contain high levels of naturally occurring manganese.

Photo: Inyo Pools

Remember, early identification is key to tackling metal stains effectively. Learning to mark and identify various types of stains will help you tackle the problem before it worsens.

How to Prevent Metal Stains in Your Pool

Of course, it’s always ideal to stop any staining from occurring in the first place. So, how do you prevent metal stains from popping up?

Test for Metals Regularly

Metals can creep into your water in all sorts of ways: through the plumbing, old pool equipment, and even your local water supply. Test your water for the presence of metals regularly, at least once per week, to keep ahead of potential contaminants sneaking up on you.

Inspect Your Plumbing

Keep an eye on the pool’s pipes and various fittings. Inspect them for signs of rust and corrosion, especially if they’re made of copper or galvanized steel. If you notice any parts beginning to rust or deteriorate, replace them.

Maintain Chemical Balance

Maintaining a proper chemical balance is extremely important in preventing metal stains. Keep your pH levels at 7.2 to 7.8 and total alkalinity levels at 80 to 120 ppm. Further, chlorination (at sensible levels) oxidizes and breaks metals down. Superchlorination, or pool shock, also acts as a periodic preventative measure.

Sequestration and Chelation

Using sequestrants and chelators is not only a great way to clear up metal stains but also a great way to prevent them. This is because such products bind to metal ions, which halts potential stains from occurring.

Filter Regularly

Do you run your pump and filter for enough hours every day? Make sure you are running your filter for at least 8 hours per day; this removes metal particles before they settle in and stain the surfaces. Plus, you could consider using a metal filter attachment that goes over the end of your hose when you’re filling your pool with fresh water—this will filter out incoming metal contaminants.

Cover Your Pool

A pool cover offers a variety of benefits. Covering your pool when it’s not in use lessens its exposure to rainwater, which can carry a variety of chemical and metal contaminants into the water.

Get My Free Pool Care Checklist

Download my free, printable pool maintenance checklist to help you accomplish regular pool care tasks for any type of swimming pool.

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Frequently Asked Questions

What does an iron stain in a pool look like?

An iron stain in a pool can take on a variety of appearances but most commonly ranges from brown to rusty, reddish brown on rough surfaces like concrete, and a deep, dark orange. It often appears as a long streak since it stems from some sort of corroded equipment.

Does chlorine get rid of iron?

Chlorine doesn’t directly remove iron from the water. It can, however, indirectly help control iron staining since it oxidizes iron, which precipitates out of the water in particles, which are then captured by the filter. Chlorine also prevents the formation of biofilm, which reduces the surface area available for iron to stick onto.

Will pool shock remove stains?

While it won’t omit metal stains from the pool completely, pool shock can boost the removal process. Plus, shock will remove most organic stains.

Have a Stain-Free Pool

Metal stains can be a real sore sight in your pool. But equipped with knowledge, you’ll be able to tackle the metal stains in your pool and remove them entirely. Remember, patience is key! With some persistence, the right approach, and a bit of old-fashioned elbow grease, you’ll have your pool sparkling like new in no time.

Do you have more questions on how to remove metal stains from your pool? Feel free to reach out to me; I am happy to help.

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