All About Metals in Your Pool with Joe Laurino

Metals in pool water are one of the most common reasons otherwise clean pools end up with ugly stains, tinted water, and frustrated customers. The key idea from this conversation is simple: sequestering agents help manage metals, but they do not remove them. Dissolved metal ions can stay in circulation and later oxidize from chlorine or oxygen, turning into solids that “plate out” on plaster, steps, and fittings. That is why a true pool metal removal approach matters, especially when draining is expensive or impossible. Joe Loreno explains how the Culator polymer works differently by binding metal ions while the polymer itself does not dissolve, letting you physically take metals out of the system.  

To solve a problem, you also have to know where it starts. Common sources of pool metals include fill water and source water, pool equipment, certain pool chemicals, filter media, plaster and masonry materials, and metal parts in water features. Outside the pool, runoff can bring metals from deck materials, landscaping products, and even roof or gutter systems, especially because rainwater is naturally acidic and can leach metals. For pool service pros, prevention is often about inspection as much as chemistry: check grading around the deck, watch for planting beds higher than the pool, and identify any copper gutters or metal roofs that dump water toward the pool.  

Stain identification is where many metal stain removal attempts go wrong. Before guessing “iron” or “copper,” first decide whether the stain is organic (carbon-based like algae, leaves, oils, or tannins) or inorganic (metal-based). A practical field test is placing a chewable vitamin C tablet (ascorbic acid) on a stained area for about 30 seconds. If the stain lifts, it is almost always a metal stain; if it darkens or does not move, it likely points to organic staining. Color can offer clues, but it is not definitive: brown often suggests iron, blue or green may involve copper, and the distinctive purple “Barney” look can signal a copper-cyanuric acid complex.  

Pool water testing for metals also requires nuance. Many technicians rely on copper and iron tests, but results can be misleading if the metal has already plated onto surfaces, leaving little “free metal” in the water. Another common pitfall is not knowing whether a test measures total metals or only free metals. If a strong sequestering agent is present, a “free metal” test may read low even when the pool still contains a significant total metal load. The best practice is to pair testing with chemistry behavior: if vitamin C removes the stain, treat it as a metal issue even if the water test reads near zero.  

The no-drain metal stain eliminator strategy described here follows a clear three-step process. First, use acids to reduce the stained metal back into solution, typically combining ascorbic acid and citric acid to cover both copper stains and iron stains when you are not fully sure what you have. Second, add a liquid sequestering agent to “coat” the ions so chlorine can return without immediately re-staining surfaces. Third, run a Culator 4.0 in the pump basket so circulating water repeatedly passes through the polymer and the metals can be pulled out over multiple turnovers. Expect temporary cloudiness as chlorine reacts with excess acids; with balanced pH and restored chlorine, clarity returns while the bag changes color as it collects metals.