The amount of sodium thiosulfate required can vary with the pH of the water. A range of approximately 2 to 7 parts sodium thiosulfate to neutralize one part chlorine is generally suggested. To neutralize 1 liter of a 200 ppm chlorine solution, approximately 0.4 - 1.4 grams of sodium thiosulfate would be required. To neutralize one gallon of a 200 ppm chlorine solution, approximately 1.5 - 5.3 grams would be required.