Hi pool doc.thanks for the response. The sequestering agent is Sparkle Conquest, manufactured by Alden Leeds Inc.. I added one quart per 20,000 gal.. total added was four quarts for 80,000 gal. I had an independent lab do water test on our supply water and pool water. The lab says that mg/L is the same as ppm (parts per million). supply water test is as follows: iron= not determined, magnesium= 5.38 mg/L, copper= 0.134mg/L, and manganese= 0.0232mg/L. pool water test is as follows: iron= not determined, magnesium= 35.8mg/L, copper=0.0047mg/L, and manganese=0.0111mg/L. what is the bucket test? I was not able to do direct reply and had to start another thread…thanks for your time…pooltech..