As the worms process the material at the bottom of the bin, it will become mostly castings. When that happens, the worms will move up into the "fresher" food. If your composting chamber is deep enough (it looks like yours is) the bottom few inches in the bin will generally always be pure, or nearly pure castings that the worms are no longer eating. As for the bottom being wetter, that is true with Rubbermaid bins, but in a flowthrough bin, the bottom is exposed to the air, so it may be drier than the bedding above it. It depends on how you manage the moisture in the bin. You don't want the bottom to dry out, since dry castings become hard and difficult to harvest.

Otis, Before you build your composter I think you need to take into consideration the weight of the compost. I am just in the process of replacing a hanging bag bin. It was hanging from 1/2 inch rods. And they bent. I took out 10 gallons of compost and they are still bending. Finished or nearly finished vermicompost is extremely heavy. Nylon rope will stretch. Have you considered if the ropes will hold the load of the finished compost or how you are going to get your knots untied with all that weight pulling them tight. I am currently building a blue barrel composter and i purchased a dolly to sit it on. I don't believe i will be able to move even a half full barrel without it. The dolly is built for a large tool box and is rated at a thousand pounds. I am hoping that the dolly will hold up under the weight of a full barrel.

It's been about 4 days and I think the worms are doing great. I didn't prep the bin ahead of time, just soaked some newspaper and cardboard for about an hour and mixed it with UCG. So I was a bit worried. But I fed them for the first time yesterday, just a little leafy greens, they are all over it. Today I put more food on other sides of the bucket. I took 1/4 avocado, spring mix, UCG, and cucumbers and chopped in in my blender. I figure I won't bother them for a week at least and see they like that combination. I'll post pics soon.

I have a bin where vermicompost does not fall through 3" by 3" holes on it's own. I have a bin where vermicompost does not want to fall through 7" by 7" holes on it's own. When I can entice the vermicompost to fall through, flow through?, it wants to fall in a column from the bottom all the way to the top. My vermicompost is not reading the instructions of how I am imagining my flow through to work. Huge flowthrough systems solve this by using precomposted cow manure. This flow through concept has not caught on in my toss in an apple core, toss in an egg carton flow through system. I do get the benefit of air at the bottom of the system. Moving bins around with 3 and 7 inch holes in the bottom is always exciting. I see your system is attached to the base with ties. It would be cool if the base was inches bigger and you could push the bin around back and forth over the base to harvest. This would take the place of a harvest bar.