You don't have to keep adding buckets on top. As you said, the bottom bucket will get compressed. You could just start a parallel system. When I had a stacking system, not ll worms travel to the top as they were supposed to. It's also possible, once the compost above is too deep, they're trapped down there.

Try bury worm food in a plastic netting to bait the worms. Remove them from there every now and then. Sometimes I just use a 4" nursery pot buried on its side for easy access by worms.

I don't know what a worm bucket tower is. Is it a commercially available system?

In any kind of multi-tray system, the potential exists for the bottom trays to become compressed unless there is something physically preventing them from nesting all the way together. For instance, on the Can O'Worms (if I recall correctly from when I had one) there is a ridge in the plastic that stops the trays from nesting together, but in the Worm Factory, the trays do nest all the way together when they're empty.

I found that the material in compressed lower trays tends to stay too wet and not break down quite as effectively, so in my current Worm Factory I put small jars or clay plant pots into the four corners of the trays to keep them from pressing down. I've been very happy with the results since doing this.

The ideal of a multi-tray system is that the worms will all move out of the "finished" trays. In reality, this never really happens all the way. The worms like "finished" material quite a bit and will go on living in it for a very long time. Even if it seems like all the visible food scraps were eaten long ago, in reality it seems that the microorganisms that the worms are eating keep living in "finished" material for a long, long time. If it looks finished, it is finished enough to use in your garden, but if some worms are still in there, you have three options:

(1) Just go ahead and use the material from the finished tray in the garden, worms and all. If you have a mature worm bin that is full of plenty of worms, you probably won't see any reduction in efficiency from the loss of a certain percentage of the worms. But don't put material that is full of worms into potted plants. They won't hurt living plants, but they'll find the potting soil too dry for them, crawl out, and likely die all over your patio or windowsill and make a sad mess.

(2) Remove the material in the tray and separate the worms out by hand. Use the vermicompost in the garden and return the worms to the bin.

(3) Remove the material in the tray, chuck it into a separate bucket, and leave it for a while with fresh food in the top. You can use a mesh bag for this. Many of the worms will gather around the food and can be removed more easily.

Thank you 11otis and theparsley for the great advice. Yes I will start another parallel system and also try using a plastic netting or mesh bag with food to attract the worms to remove them. I adopted the homemade worm tower from someone. It's buckets with holes drilled on bottoms and sides and stacked on top of each other. I have everything in the garage so was trying to save space but I will make space for another parallel system and later for the mulit-tray Wriggly Wranch. I like the idea of small clay pots to keep from pressing down. I will try that with the tray system because the buckets do not have enough surface area. I'm currently using small pieces of wood blocks on some of the buckets to reduce the compression.

I have been separating the worms out by hand but will try your #3 to save time.

I can see how regular old buckets might have some drawbacks as a worm bin system. Worm bins (or the individual trays) do better if they are more on the wide and shallow side because you need lots of surface area. The Wriggly Wranch should do fine.

And the trays do not need to be touching the material in the tray below - worms can scale up the plastic inner walls just fine, as long as it's properly moist in there. They will also happily climb up and down plant pots or whatever else you might use to prop the layers apart.

Here's my bucket setup at the moment. I started off with less than half a handful of worms about a year ago. Now there's a ton of red wigglers.

snuffles, IMO remove the lowermost bucket and transfer the castings(including worms) to a separate container. If those castings are too wet to work with then place some newspaper in the bottom of the bucket to absorb some of the excess moisture. Once the castings look a little drier, dump everything out into a pile on a plastic sheet in direct sun if you can. Give the worms 10-15 min to escape the direct light then harvest the castings from the top of the pile. As soon as you start noticing worms again wait another few minutes and repeat harvesting. Since most of your worms are working up where the food is I'd bet there aren't too many worms in the lower bucket anyway.

I say harvest some of those precious castings and get them working for you in your garden.

Good luck,

Harry