I love my tumblers. They work really well for fast composting once you figure out the art side of it. Getting the C:N (brown:green) balance right is a bit of art. You can speed up the learning or figure-it-out process by getting to know the C:N ratios of what you're using as feedstocks. How full is optimal may depend upon the specific tumbler you have, but in my experience with two different brands, both horizontal drum types, they work best at about half-full. I use two 90-gallon tumblers. Using aged shredded wood mulch as browns and kitchen produce trim + UCG as greens, it takes me about 4 weeks to half fill one. During the fill I do not tumble, but layer. I've found it seems to work best if I start with a couple of inches of wood stuff, then add the greens as mini-piles 2-4" thick, covering each with more wood mulch for every addition. I do NOT mix during this build-it-up period, by do water starting after about two weeks (the mulch is really dry and soaks up a lot of water. How much is a learned thing. After it's half full I start the daily tumbling, six revolutions. It takes about 4 weeks to get to mature compost. I use an old fashioned 4-tine cultivator (think pitchfork with bent times) to pull the stuff from the ends towards the center after each tumbling session - it helps with the heat-up in what would be a shallow pile.

I "harvested" my compost today from one side of my Mantis Compost-Twin. It looked about half full, way less volume than I started out with. I dumped out two small wheelbarrow loads, and now it does not look like there's much left in it at all. Cranking it is ridiculously easy now, so that confirms there is not much left. I had been daydreaming about what all I'd do with my compost when the first batch got done. I've gotten a jolt of reality, I guess. Where I was thinking of putting inches of compost on the first flower bed that I worked on, the reality was I put a few shovelfuls sprinkled here and there, and that was all I had in the small garden wheelbarrow. I'm not giving up on composting or anything like that. But at this rate, it will take me a decade or two to do much to my flower beds. There is a local botanical garden which offers leaf compost loaded into your truck for a donation. I guess I need to explore that possibility. Sadder but wiser Jim

It's a tumbler on a raised reservoir designed to catch any runoff. I add liquids from the kitchen, and water once a month. Between that and what naturally occurs as the mix decomposes I got a few gallons in about a year that I've used it (didn't cap the reservoir, so there was likely evaporation). I just didn't want to feed the wrong thing this fall. Here is a link that might be useful: Pic on left

I've never bought a tumbler but I use three different sized ones, all home built. They all work well for what they were designed/intended for. They certainly can have issues if one attempts to use them for something way beyond what they were designed for. I also agree that the advertisements are, how can I say this politely, embellished a tad. There are definitely people that hate them and there are people that love them. I would recommend that people seek out local gardeners or clubs to see if anyone close to you has one you can go look at before one makes an aye or nay decision. Most compost whackos enthusiasts are more than happy to show off their compost equipment. Stealing Borrowing an idea/design isn't cause for shame in the composting world, I've done it often enough. (Thanks Vance, squeeze and gonefishin) Over the years the discussion about the practicality of tumblers has gone on and on and on and on. Someone once likened it to the tastes great/less filling debate, I tend to agree with that assessment. Lloyd