If waiting isn’t your style, or you have a covered pool, you need a chemical neutralizer. The two most common are sodium thiosulfate (sold as “Chlorine Neutralizer” or “Chlor Out”) and hydrogen peroxide (pool-grade, not the brown bottle from your pharmacy).
Sodium thiosulfate is the gold standard for a fast fix. You add a small, calculated amount based on your pool’s volume and the current chlorine reading. Within 15 minutes, you can see a dramatic drop. It’s like hitting the undo button on your last shocking session.
A fun cultural reference: pool technicians in Australia often call sodium thiosulfate simply “thio,” and they use it like emergency brake for water. In the US, it’s the secret weapon for pool stores when a client’s water looks like a bleach bottle exploded.
Hydrogen Peroxide: The Alternative Path
Pool-grade hydrogen peroxide (typically 27% or 35% concentration) is another effective option, especially if you’re running a saltwater or mineral pool. It works by oxidizing the chlorine directly into salt and water. This is a gentler approach that doesn’t mess with your pH as aggressively.
But here’s the catch: don’t mix hydrogen peroxide with biguanide (a non-chlorine sanitizer found in some systems like Baquacil). That combo creates a chemical fog that can actually cloud your water into a milky mess. Always check your label first.
For the DIY crowd, a little hydrogen peroxide goes a long way—one quart of 27% hydrogen peroxide can treat roughly 10,000 gallons of water for a 1–2 ppm chlorine reduction.
11 Easy Tips: Lower the Chlorine Level in your Pool.
