So you really dont need a ato?The best ATO on a small nano is a 2 liter bottle of diet coke filled with RO/DI water that you manually add daily. If you go on vacation for a week or more. Just add a tad bit more with cover and when you come home you'll still be spot on. LOL Cheap, easy and effective. PS ( must be Diet Coke bottle ) cuz I don't like Pepsi haha