Copper Stains in Swimming Pools
copper stains in pool surfaces
Copper stains in pool surfaces can be particularly stubborn because copper won’t react to chlorine, algaecides, or brushing. These stains are also tricky because they can appear in various colors, ranging from pale mint green to light brown or gray. Also, the color varies depending on how long they’ve been present in the pool. Copper stains may show up on both the walls and the floor of the pool.
Often, pool owners mistake copper stains for black algae due to their green or dark black color. When this happens, they attempt to remove it by shock-dosing with granular chlorine. If they do this, the copper stain quickly turns black as the chlorine oxidizes the copper on the pool surface.
Our powerful treatment will remove copper staining from swimming pools without draining or acid washing.
What causes Copper stains?
Copper staining in pools happens because of the introduction of copper sulfate through products like algae blocks, copper-silver systems, cheap pool salts, or copper-based algaecides. These products release millions of invisible copper ions into the water. If these ions aren’t properly managed or removed, they can bond to the pool surface, leading to ugly copper stains.
Copper staining is often triggered by water imbalance, especially when pH levels rise above 8.3. At higher pH, copper ions are more likely to ‘plate out’ or adhere to pool surfaces, creating stubborn discoloration.
In some cases, unbalanced water can ‘draw out’ copper from copper plumbing in older gas heaters, introducing even more copper into your pool. Fortunately, most modern heaters now use CPVC, or Titanium pipes that don’t contain copper.
Chlorine turns copper black
Even without shock chlorination, copper stains in swimming pools can darken and become discolored over time due to exposure to dirt, chlorine, and other minerals. This can cause the stains to take on a range of colors and shades across the pool surface.
Remember, copper stains often resemble green algae in color, which can lead to misdiagnosis and incorrect treatment. In fact, copper stains are the most commonly misidentified pool stains we see. Even experienced pool guys get it wrong!
Signs of copper staining
- A colored stain that won’t brush away
- The stain gets worse / darker over time
- Stain slowly changes color and spreads
- Chlorine shock treatment makes the stain darker
- Copper levels seem to be dropping for no reason
Many clients who see a green stain in their pool think they’re dealing with green or black algae. They’re often surprised when our treatment (containing no chlorine or algaecides) completely removes the stains. So what’s the reason? Copper behaves very differently in pool chemistry, which is why traditional algae treatments don’t work on copper stains.
Copper Stain Removal
Copper Stain Removal - DIY kit
- 1 bottle (64oz) of a copper stain prevention polymer
- 9 lbs of copper stain-dissolving compound
- Phone support from our technicians
- Simple step-by-step video instructions
- Pool does NOT need to be drained or acid washed
- Kit is shipped and tracked by UPS
- Kids are back in the pool in just 7 days
- Kit is $295 for pools over 12,000 gallons
Copper Stain Removal –
On Site Technician
- 1 bottle (64oz) of copper stain prevention polymer
- 9 lbs of our copper stain dissolving compound
- Complete 7 point on site water testing
- Your pool does NOT need to be drained
- Kids are back in the pool in 7 days
- Visit is $405 for pools over 12,000 gallons
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How did copper get in my pool?
Many pool owners are puzzled by copper stains in their pool, especially when they believe no copper has ever been added. However, copper can enter pool water in several unexpected ways. Here’s a brief overview of common products that may introduce copper into your pool.
- Copper based algaecides
- Contaminated Low quality pool salt
- Old pool heater with copper piping
- Copper sulfate tablets (aka algae blocks).
- Well water high in minerals
- Chlorine free pool systems (copper/silver)
While copper-based products are great at killing algae, they come with a big risk. If you don’t manage or remove the copper levels during and after treatment, the metal can settle and stain your pool’s surface. We often hear from clients who had perfect pools for 15 years, only to end up with dark stains within weeks after using a copper product for the first time.
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Remove copper stains from pool surfaces
Our copper stain remover is effective on all pool surfaces, including PebbleTec, plaster, fiberglass, DiamondBrite, Marcite, and fully tiled pools. As shown in our results, we remove copper stains from pool surfaces without the need to drain your pool or acid washing.
For severe staining, we recommend using CuLator Metal Eliminator alongside our treatment to physically remove residual copper from the water and help prevent future staining. Doing this will ensure the copper never returns to stain your pool again.
Not sure what type of stain you’re dealing with? Don’t worry, we’re happy to help—just get in touch with our team.
Remove copper from pool water
For pools with heavy copper staining, we recommend using CuLator Metal Eliminator alongside our stain treatment. While our treatment removes copper stains from pool surfaces, it does not physically remove copper ions from the water. If copper ions remain in the water, there’s a risk that they will re-stain the pool over time.
Unlike pool store ‘metal removers’ that merely suspend copper ions, CuLator actively removes them from the pool water. For best results, test the copper levels during and after our treatment and then add CuLator if any copper is still present in the water after the stains have gone.
Frequently Asked Questions
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Will acid washing my pool get rid of copper stains?
While a traditional acid wash may remove surface stains, it is so aggressive that it damages your pool’s interior. Most acid washes are well over $1,000 and you will need to replace all of your pool chemicals and your pool water! More importantly, if the copper has been there for more than 1–2 years, it may have been absorbed deep into the surface, making it resistant to acid washing. Our treatment is designed to lift the metal safely without the need for draining or harsh scrubbing.
Is it safe to swim in the pool while treating copper stains?
Yes! Unlike many heavy chemical treatments, our copper stain removal process is swimmer-friendly. You only need to close the pool for 7 days. However, we recommend following the instructions provided in your kit to ensure the chemistry is balanced before swimming.
Will the stains come back after the treatment is finished?
The stains will only return if the source of the copper isn’t addressed. Once our product lifts the metal off the surface, you must physically remove it from the water with Culator. We also recommend using scale and stain eliminator to stop dissolved copper from re-staining your pool.
How can I tell if the stains in my pool are copper stains and not algae?
Copper stains often appear in colors ranging from pale mint green to light brown, gray, or even black over time, usually on walls and floors. Key signs include: the stain won’t brush away, it darkens or worsens with chlorine/shock treatment (chlorine oxidizes copper, turning green areas black), it spreads slowly and changes color, and water copper tests may show levels dropping to zero as the copper plates onto surfaces. They’re frequently misidentified as black algae because traditional algae treatments (brushing, algaecides, shocking) don’t work and can make them look worse. If you are still unsure, please contact us and we can help you.
