I purchased a new Protank II last week after my first cleaning noticed rust at the top of the airflow tube where it permanently meets the crossbar. The tank came in the Kangertech box. The juice used in it was Epic's Banilla. I cleaned it using only hot water, dried it with paper towels and set it on the counter overnight. By morning, I noticed there was rust, though I could not tell you if it had always been there. Of note, I'm somewhat meticulous by nature and it wasn't exposed to anything except what I write here. The rust is not to be confused with gunk, as it is most certainly rust after close inspection with a magnifier. Since that cleaning, I've used Vodka (high quality) to clean following advice on another thread. Now my questions... Have you seen this happen before? Can you point me to a glass tank (or is it atty?) that can be relied upon? I'm still learning and while I'm stowing away bits and pieces of information on cartos, I don't think I'm quite there yet (unless you can prove otherwise to me how easy it might be). Thus, do you know a good thread you could point to that discusses them for new users?