Julian GonggrijpA friend rightly pointed out that I should share more of my creations with the world. So for starters, here is the flow-through #vermicompost bin 🪱 that I built two months ago. 🧵
#sustainability
#sustainability
I made it from an old, more cylindrical plastic trash bin, a garbage bag, wood, linseed oil, galvanised steel screws and wire and two small weels (not visible on picture). It was directly inspired by the #HungryBin, which I wanted, except that I needed something smaller.
I ordered a mix of red wigglers and European night crawlers online. The initial feeding included the sawdust and leftovers of the wood I used in building. I also introduced predatory mites to preempt insect infestations and some healthy forest floor to kickstart #biodiversity.
They have now been living in the bin for 7 weeks. The mite population exploded within the first days and then stabilized. About 3 weeks in, I spotted the first baby worms and the surface was steadily sinking. White mites appeared a bit later, after I added the first watery food.
Feeding has largely consisted of dead Christmas tree, used potting mix, tissues, coffee filters and tea leaves. I occasionally added ground eggshells. I checked the smell daily, which was generally good: subtle and foresty, with just a hint of coffee.
However, starting 2 weeks ago, I did occasionally see a dead worm that seemed to have constricted sections. 4 days ago, I decided to look it up. I learned about protein poisoning 😱 and figured that I had been giving too much coffee grounds and not enough eggshell.
I dug about 15 cm deep in order to earate the mix and discard anything nitrogen-rich, uneaten or stinky. At that depth, I hit almost solid black gold. Also reassuringly, I encountered mostly healthy worms. I layered back the materials with extra carbon and crushed eggshell.
I have not yet seen dead or constricted worms since. I did see baby worms and noticed that the surface is still sinking, so the worms seem to pull through well. 😅 I will carefully try some worm chow with ample carbon and eggshell in 2 days or so.
I will add to this thread when I have further updates. Among other things, I intend to write a more in-depth article about the construction and startup of the bin eventually.
I realized that the bin is also very wet, probably because the remaining coffee grounds are decomposing. I decided to not add any fast food for the time being. I added more paper and eggshell and will be opening the lid every day until the moisture level seems good again.
Four days ago, I decided to drill extra holes in the lid to reduce condensation and improve aeration. I was still seeing healthy adults and babies when digging, but a few more constricted worms did appear in the meanwhile. Condensation reduced substantially, so I now keep the lid shut again.
Today, I added a tablespoon of worm chow in one spot and covered it with a big handful of aged bedding. I will be carefully pocket-feeding the worms once a week, monitoring closely how much they can eat.
Just checked in on last week's worm chow feeding. I could still see the chow, but there were LOTS of worms in the material around it. 🪱😍 That gave me enough confidence to give them a new pocket feeding with a coffee filter that had been pre-fermenting since last Wednesday (I stirred a fingertip of worm poop through the grounds in order to kickstart fermentation).
I also picked up 10-ish woodlice from my balcony and introduced them into the bin, so they can help chew the fibrous materials.
Checked in on the last 2 feedings today. I saw several worms nearby, but there was still some worm chow left. The coffee grounds were rather dry and didn't get much attention from the worms. I skipped this week's feeding, placed a wet paper towel on the coffee grounds and also placed ice cubes on the bedding above both feedings.
I noticed that the newspaper cover is getting serrated edges since I introduced the woodlice. Bedding is shrinking quickly, definitely a lot of activity in there!
Both of the previous feedings were gone today. No trace! The coffee filters I covered them with, also gone, and also much of the bedding I put on top. Worms of all sizes everywhere. This bin is booming! 😍
Five months in, first harvest! 🪱
✅ harvest from the bottom
✅ only the contents I wanted to take out came out (needed to scrape)
✅ just castings (and some undigested wood), no worms
✅ slightly moist but powdery and non-smelly
I'm still slightly worried whether the remaining contents will eventually settle down or whether I will have to stir the bin with a broomstick. Other than that, this self-built flow-through worm bin is living up to its promise!
After sifting out the wood chunks, I was left with about a liter of fluffy, almost pure worm castings. I already used some of it to make a simple worm tea in aerated greywater. I sprayed and watered all my house plants with the tea, then gave the solid residue to the plants that needed it most. I will use the remainder for prefermenting purposes and occasional plant care. 🌱
The drainage holes in the bottom dish held a tiny surprise. Some mystery organism sealed about half of the holes with a hard, almost plastic-like substance. If anybody can explain to me what this is, please do! #biology
(Regardless, I unblocked the holes with a used toothpick. The material that I poked out and the toothpick were fed back to the top of the bin.)
All these months, a jar with a funnel was standing under the drainage holes in order to catch any leachate. 💧 I tested the drainage when I put the initial bedding in the bin and it worked, but after the bin entered operation, not a single drop of liquid hit the bottom of that jar. I will not put it back, because it is a hassle to keep it centered with the drainage holes.
Let's call them "bottom air holes" from now on. 😅
On this picture, you can see that the air holes in the top lid have filthy edges, probably due to worms and mites making brief excursions. I never see the worms actually do that, but I suspect they do because they crawl on the inside of the lid and they would easily fit through the holes. The (brown) mites run everywhere over the outside surface, not just around the air holes.
To finish this update, here is an image of the top of the bin just after opening the lid. You can see young worms on the inside of the lid. The banana leaves on top have jagged edges and gaps due to woodlouse chewing. With some creative interpretation, you can distinguish patches of slime mold near the right hinge, one on the inside of the lid and two on the banana leaf.
Next episode when I know whether the bin settles itself or not! 🪱
🧵 Nine months in, I'm sure that my self-built vertical flow-through worm bin 🪱 does not settle by itself, or at least, not fast enough.
After a harvest, there is a void in the bottom of the bin. Some worm castings fall down from the bottom surface of the bin contents, so there is a little pile of castings when I detach the bottom dish on the next harvest. However, the bulk of the bin contents does not seem to sink much and the top surface keeps slowly rising.
On my last harvest, I took a risk and continued scraping from the bottom surface until I reached over half of the bin's height. At that point, the bin contents were *still* staying in place. I then realized that worm castings are extremely cohesive, and that even a slight constriction is enough to hold up a large amount of material.
My plan? I don't want to have to regularly stir or kick the bin in order to force the material down. By freak accident, the design of the bin gives me another option: I can change its shape.
I have removed the top two steel wires, in order to release the width constraint from the upper half of the funnel. Over the next few weeks, I will allow the bin contents and gravity to gently push out that constriction. If needed, I will help this process a little by sticking in my arms from the bottom and pushing against the inside.
Eventually, I will also remove the third wire and then reinforce the shape again with new, longer wires. The shape I will work towards is quite different from what I have, but it will still fit in the frame. The top 80% will be nearly straight, while only the bottom 20% will narrow down. Hopefully, this will flow better. In any case, the bin will be able to contain more material in this way. 🤔
Credits to Tom Mills from GreenShortz DIY, who published this video seven years ago:
https://www.youtube.com/watch?v=2smEluKUaJw
I watched that video long before I started building my own bin, but did not like Tom's design at the time. I did not like the shape, which seemed to rely on strings in order to hold up the material, and the strings themselves, which I thought complicated harvesting. With hindsight, I think his design does not actually need those strings and he is right about the shape!
How To Make A Flow Through Worm Composter
Just peeked into my worm bin out of curiosity. The most recent feeding, from last Saturday, was covered in a LAYER of worms. I could only just see bits of the underlying material between the worms, it looked exactly like a worm ball! I could literally HEAR them SQUIRM! 🪱🪱💕
Possibly relevant recent changes:
🪱 prefermenting all greens with lactic acid bacteria
🪱 not adding dry bedding (only damp) because I realized the bin was a bit dry
🪱 perhaps just population growth
It is nearly two years since I last tooted about my #vermicompost bin. There are simple reasons for this: the system stabilized, I got used to it, and other matters in life distracted me from writing about it. There is, however, a recent development that warrants another update. In short, ... *takes a deep breath*... I feel disappointed by my own #design and I want a different bin. Let's explore this. 🧵🔽