Horrible diaper rash from calgon?

[mama c.]

We have been having stink issues with our diapers (mostly bumgenius hand me downs) I just found out we have really hard water in our well. I tried calgon in this last wash but must have used too much or not rinsed enough because my daughter has this horrible painful bleeding rash all of a sudden that looks like a burn.` Is this common from the calgon or could it be something she ate? She's never had a rash like this before, is there something specific I should do for it and what is the proper treatment for hard water? There is so much info out there its mind boggling!
Thank you!

[thefreckledmama]

The first thought I had was that the diapers weren't rinsed well enough. The softened water from the Calgon probably helped a lot of the old residues to start working out of the diapers. If your water was especially hard, it could take multiple rinses to remove all of the residues-adding vinegar to the rinse might help too.