I've been cleaning tanks like crazy.. you can't believe the condition some of the used tanks I bought are in (dirt cheap). Use a spray bottle to get a good spray of vinegar over the deposit, let it sit, and either use a razor blade or a good scubber. A good scrubber, I used a metal one that kinda looks like steel wool, will even get the stuff that's is caked onto the plastic. I got vinegar at the dollar store. I'm not sure about the red wine vinegar but if I was you, I'd go for it and just wash out with water.