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. 🧵🔽
Before I dive into the reason for my disappointment, let me quickly update you on the changes that I made to the bin during the past two years.
🪱 I changed the shape. The top 80% of the bin is now more or less straight, only the bottom 20% tapers inwards. I previously announced this plan in https://ieji.de/@juliangonggrijp/111524084659269125 and following toots.
🪱 I replaced the bottom lid, which had a circular pattern of small holes in the center but was otherwise closed, by a 5 mm gauge sieve grate. This allows more air into the bin and enables the castings at the bottom to start drying already before I harvest them.
🪱 A low, wide salad bowl is suspended under the bottom grate. It contains freshly harvested castings. This lets the castings dry further. At the same time, it offers a hospitable landing site for #worms and #woodlice that fall out the bottom of the bin.
🪱 A colander is perched on the lid at the top of the bin. It contains the previous, older and dryer batch of harvested castings. Worms that ended up in the harvest can crawl back into the bin through the holes in the colander and the lid.
Julian Gonggrijp (@[email protected])
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.
With this setup, I settled at a steady rhythm. I feed the worms every six days, which I dub a #wormWeek. I alternate between two spots, left and right. There is a third spot which I never feed, at the back. Theoretically, I might skip a feeding if the worms didn't finish the previous feeding in the same spot, but this almost never happens anymore. The feedings have a consistent size, because I buffer them in external containers, and I know the animals can keep up with this ration.
Every day, I scrape a layer from the top of the colander and sieve it. What falls through the sieve are my finished castings, ready to use. What stays behind goes back in the top of the bin. When the colander is almost empty, I refill it with the contents of the salad bowl and I open the bottom of the bin to refill the bowl. In this way, the bin, the bowl and the colander form a #cycle, but with a net outflow at the colander and a net inflow at the bin.
For the most part, it works really well. This relatively small system can eat nearly all #biodegradable #trash from my two-human, two-cat household. (Yes, even the cat's kill goes in sometimes). Only when I suddenly have a lot of trash, it might not all fit in the external buffers and I might have to discard some with the general waste. The compost worms, potworms and woodlice seem very happy. I get a steady supply of high-quality #wormCastings from it. I produce so much castings that I am constantly giving them away to friends and family.
So why am I disappointed? Because my bin fails at its core #design goal, to make harvesting easy. It fails in three ways.
Firstly, this is supposed to be a continuous vertical flow-through worm bin, but moist worm castings just do not #flow. Not even downwards. Not even when they are in a wide, straight, vertical tube. They form a sticky, coherent, muddy cake that plasters itself to the inside of its container. When I harvest from the bottom, I create a pocket of air that just stays there. I mean, the air pocket will migrate upwards *eventually*, because small amounts of castings crumble off above it and resettle below it, but in the meanwhile, the contents of the bin will overflow with the newly added material at the top. I have to use violence to force the castings downwards.
Secondly, the challenge for any worm bin design is to separate the castings from the worms, but what falls out the bottom of this bin? You guessed it, castings AND worms. (I got pure castings the first time I harvested, but with hindsight, that was probably a special condition due to the recent start of the bin. https://ieji.de/@juliangonggrijp/110885281283201294) Due to gravity, moisture in the bin concentrates at the bottom, and worms like moisture. The grate partially adresses this, but not enough to keep the worms away. The colander is, essentially, a workaround so that I can still sieve castings without torturing worms. It looks rather improvised and that is exactly what it is.
Julian Gonggrijp (@[email protected])
Attached: 1 image 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! #vermicompost #compostodon #wormodon