A pool can look perfect on Friday, then turn an eerie green tint right after you shock it and suddenly everyone swears it’s algae. We’ve seen it on routes and heard it from homeowners: clear walls, no visible growth, but the water has a strange color cast that shows up fast. The fix starts with stopping the guesswork and running a simple, chemistry-driven test that tells you what you’re actually fighting. 

We’re joined by Joe  Laurino of Culator Products to unpack the real causes of tinted pool water, including organic haze from tannins and humic acid after a fresh fill, and the metal-driven color shifts that appear when chlorine oxidizes copper or iron. Joe explains a practical field method: add ascorbic acid and watch what happens. If the tint snaps to crystal clear, you’ve likely confirmed metals and can move to the right next steps, including a sequestering agent and a metal remover like CuLator 4.0, instead of endlessly shocking and brushing. 

We also get into the “purple dust” many techs now find in skimmers and cleaner hoses. Joe breaks down why it forms when copper meets cyanurate, how trichlor tablets push cyanuric acid (CYA) higher over time, and why high stabilizer levels can weaken chlorine and create a cycle of relying on copper products. Then we tackle the curveball: iron bacteria. If a stain disappears with ascorbic acid but returns within a day or two to the exact same spot, that’s a huge clue, and Joe shares how to confirm it and the EPA-backed treatment approach using copper algaecide and high chlorine. 

If you service pools or manage your own, you’ll leave with clearer diagnostics, fewer wasted chemicals, and a smarter plan for green pool water that isn’t algae. Subscribe, share this with a pool pro who’s chasing “mystery tint,” and leave a review with the strangest water color you’ve ever seen.

We break down why pool water can turn green or tinted right after shocking even when the pool is spotless, and how to prove whether you’re facing metals or organics in minutes. Joe Loreno from Creative Products explains purple dusting, high stabilizer side effects, and the iron bacteria problem that fools even experienced techs.
• using ascorbic acid as a fast metals test for green or brown tinted water
• distinguishing stained water from a stained wall or floor
• adding sequestering agent and using CuLator 4.0 after metals are confirmed
• spotting organic tint from tannins and humic acid after fresh fills
• explaining purple dust as copper plus cyanurate from elevated CYA
• why high cyanuric acid weakens chlorine and pushes copper product overuse
• identifying iron bacteria by rapid stain return and same-spot reappearance
• using the toilet tank orange slime check to confirm likely iron bacteria
• treating iron bacteria with copper algaicide and superchlorination
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