Pool Breakpoint Chlorination Calculator

The smell isn't too much chlorine - it's too little

The sharp "chlorine smell" and eye irritation many swimmers blame on excess chlorine is usually caused by combined chlorine (chloramines), byproducts formed when chlorine reacts with sweat, urine, and other organic contaminants. The fix is counterintuitive: add more chlorine, not less.

Worked example

For a pool testing 3.0 ppm total chlorine and 1.0 ppm free chlorine:

Combined Chlorine = 3.0 - 1.0 = 2.0 ppm

Required Boost = 2.0 x 10 = 20.0 ppm free chlorine boost needed

Frequently asked questions

Why multiply by 10 specifically? Breakpoint chlorination requires oxidizing all the nitrogen compounds bound to chlorine, which chemically requires roughly 10 times the combined chlorine concentration in added free chlorine to fully break through, rather than just partially reducing chloramine levels.

How is this dose actually added? This required ppm boost is typically achieved through a large shock treatment - once you know the ppm increase needed, a cal-hypo shock dosage calculator can convert that into an actual pounds-of-shock-product measurement.