I am not going to get into this conversation beyond this one comment, but here it is...
A lot of the comments that have been made in this thread regarding well water quality and treatment options are at least partially incorrect if not egregiously so. I am not doubting anyones fish care experience or abilities, and I actually would like to give a +1 to the old water heater comment made earlier, most people don't think about that and it can certainly be a source of significant contamination. Beyond that and the comments suggesting that the well water be tested, most of the well water related information shared should be disregarded.
I worked for a plumbing systems and water treatment wholesaler for over seven years between my BS and MS studies, dealt with residential, commercial, agricultural systems, and tested water for municipal distributors. I don't wish to pick on any individual comment made, but I had several vocal outbursts while reading the last quarter of this thread... READER BEWARE! Ignorance is difficult to filter as a reader when you yourself are not thoroughly familiar with the subject matter.