How do I lower the chlorine level in my pool?

If the actual chlorine reading is not too high (i.e. around 10ppm), suspend dosing and allow it to drop over a period of time. If the chlorine reading is significantly higher, or if you need to use the pool in the near future, add sodium thiOSulphate to reduce the free chlorine. WARNING The recommended dose rate is 250 grams per 50 cubic metres. Apply this in several much smaller additions, testing after each dose. An overdose of thiOSulphate can leave you with a chlorine deficit for a considerable time.