Many on HBT have praised Oxyclean and I was skeptical. No more. I soaked a nasty carboy, with dried krausen and other gunk (technical homebrewing term there) for a few hours in a weak Oxyclean solution. No scrubbing necessary, and everything just rinsed out. Amazing. Sure, it's about $10 for a tub, but you do not need to use much. Definitely worth it. Take if from a skeptic.