Expert Verified Updated: March 2026

Chlorine Neutralizer (Sodium Thiosulfate) Calculator

Calculate exactly how much Sodium Thiosulfate you need to rapidly lower extremely high chlorine levels after an accidental overdose.

Quick Conclusion
To lower pool chlorine by 1 ppm, you need approximately 2.6 ounces of Sodium Thiosulfate per 10,000 gallons of water. Always dissolve in a bucket before adding.

Technical Comparison

Neutralizing AgentDose per 1ppm/10k GalSpeedSide Effects
Sodium Thiosulfate2.6 ozInstantLowers pH slightly
Sodium Sulfite3.0 ozFastCan create chloramines
UV SunlightFreeDaysLoss of CYA protection over time
Swimming in chlorine levels above 5-10 ppm can cause severe skin irritation, bleach swimsuits, and damage pool equipment. If you accidentally overdosed shock, you cannot wait days for the sun to burn it off.

Actionable Steps

1. Measure exactly how many ppm of chlorine you need to eliminate. 2. Calculate the Sodium Thiosulfate dosage. 3. Pre-dissolve the powder in a 5-gallon bucket of pool water. 4. Pour slowly over the return jets.

Pro-Tip

Never overshoot the target! If you add too much neutralizer, it will stay active in the water and destroy the NEXT batch of chlorine you add. It's better to lower the chlorine halfway, re-test, and then add more if needed.

Frequently Asked Questions

How fast does chlorine neutralizer work?

Sodium Thiosulfate works almost instantly. You can usually re-test the water within 30 minutes to 1 hour after adding it with the pump running.

Can I use Hydrogen Peroxide instead?

Yes, standard 3% household hydrogen peroxide can neutralize chlorine, but you need massive quantities (about 2 gallons per 10,000 gallons to lower by 10ppm), making it impractical.

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