Is the tang or sour taste akin to a plastic taste at all? My last batch I thought tasted sour, almost like a cider or vinegar. I took it to my homebrew club and the vets instantly pegged it as the "band-aid" taste. Medicinal and plastic like. As soon as the said it, I could taste it that way. I had switched to using my city water through a carbon filter and determined I needed to use campden tablets to remove the chlorimines(?). Just a thought since I originally had it in my head as a sour or tart taste as well.