I've been using One Step to clean out my carboys, usually letting them soak full overnight. I'm noticing that a ring is forming at around the top of the carboy, that I can't get rid of. It almost looks like the small bubbles that rise up and out the top are clouding the glass.
I'd appreciate anyone's thoughts on what I'm doing wrong, and whether or not I should expect to get rid of these rings.
Thank you for your help.