Tumbling relies on physical agitation to efficiently aerate the composting material in order to reach temperatures high enough for microorganisms to aerobically break down the waste in an efficient manner. This process works best when the tumbler is full, with a good balance of “greens” and “browns,” and with frequent agitation. “Greens” consist of food waste and grass clippings and “browns” consist of dry materials such as shredded newspaper, dry leaves, or sawdust. You need some “browns” in addition to the “greens” for efficient aeration, and under optimal conditions compost can be produced in as little as two weeks. Thus with two tumblers, one tumbler can collect food waste while the other is full and efficiently composting. These bins are highly aerated but completely sealed and elevated to prevent pest problems.