I have four. It takes awhile to get a layer done. Each tray has some grid holes on the bottom, and when processing a "done" tray, I didn't ever find an easy way to do it. Would just take the bottom done tray, bring it in to the kitchen bar, lay it on newspaper, use my hands to pick out the worms and put them back in the next worm tray. Scraped out the casings, and would usually get a gallon ziplock of casings (poop) from each tray. Throw that in your garden. Mine came with a dvd on how to use it and it's very easy. But I wouldn't keep it in the house. I had to keep ours moist (not wet) but I had it set up in the garage in New Mexico for a number of years (same worms) and the humidity is pretty nil there. I'm in a higher humidity place now, and I bet it would hold moisture. I really should order some worms, but I'll put it on my spring to do list. When worms get stressed they form a ball, picture a moving ball of yarn. So when you order them, they come that way.