Mark’s OSCR Videos – Part I

As a follow-up to the hugely popular post “Mark and his OSCR Worm Bin“, our roving Red Worm reporter, ‘Mark from Kansas’, has been kind enough to put together a three part video series featuring his OSCR worm bin. A couple of these videos are close to 20 minutes each so I’ve decided to bring them to you one at a time (Part II will be tomorrow, and Part III on Thursday).

This first video (which runs 18:26) features Mark talking about his OSCR system. He brings up some of the topics of discussion from the comments section of the post mentioned above, and also runs through his journal entries written since the post was published.

I have included these journal entries here so you can refer to them as well.


I notice a fair amount of moisture in the harvest chamber. I don’t think it is leach* because the water is clear, like condensation. A lot of worms have settled in the coffee layer and I found some cocoons on the top surface. I added 17 pounds of trash and covered the top with 1 lb. of leaves.

*[EDITORS NOTE]: What Mark refers to as ‘leach’ is what I refer to here on the site (and in newsletters) as ‘leachate’ – basically, the dark liquid that drains out of the bottom of a worm bin (some people refer to this as ‘worm tea’, but that is a bit of a misnomer).


I installed a 4” fan on the outside of the harvest chamber and closed the door to force air upwards. The condensation went away but the bin temp climbed to 90 degrees. I reopened the chamber door.


I turned off the harvest chamber fan.


Found 6 lost souls in the harvest chamber and the condensation was back. I turned the fan back on. The temp in the bin is and has been a constant 80 degrees. The temp in the garage is 59 degrees. I watered down the top with a ½ gallon of water.

The heater cable uses 42 watts of power and if used 24 hours a day for 30 days, it will cost me 10 cents a month based on the cost calculator:


I closed the harvest chamber door and turned on the fan. Now the harvest chamber is “pressurized” to force air upwards. Some worms are finding their way into the harvest chamber.


I layered the inside perimeter of the bin with all the coffee filters. I keep finding lost souls on the edges of the perimeter in the harvest chamber. Hopefully as the bin processes, the decomposing filters will push the bin contents and worms toward the middle. Added 12 pounds of food.


Added 5 pounds of food


The harvest chamber remains to be dry. Yesterday I added 2 gallons of water to the top. Today the HC is still dry. I poked around the top to look for worms. They are very active and react very quickly to light. The worms on top look FAT. I am hoping the bottom layer of newspaper above the HC will breach in 2 weeks. I also sprinkled 5 pulverized egg shells to the top.


I added some pumpkin guts to the bin. I decided I would only leave the pressure fan on during the day. The top 1 inch has been a little dry. Other than that, the worms look fat and alert. They dart back real fast when they get in the light. Added 13 pounds of food.


Added 8 lbs. of food topped with some leaves. I am risking overfeeding but I’ll watch carefully.


I added some more coffee filter paper around the perimeter. I put a plastic tarp over the top and left a small opening on the side a couple of days ago. I am leaving the fan on for only an hour, seems like all I do is water the thing, 2 gallons last night.

Forget about the overfeeding, the worms are over the new stuff. No bugs and the bin smells like wet leaves. Putting the tarp on created a warm and humid environment in the bin, condensation is running down the sides. The temp of the bin at a 4 inch depth has been 80 degrees F for at least a week. The worms still look fat and are very reactive to light.

So far I have added 385 lbs*. of trash to this bin. I was concerned about overfeeding.

Now, I just don’t know. I am still going to be on the conservative side when it comes to feeding. The bottom of the bin where the newspaper is has not breached yet. The very bottom layer is the finished compost and cocoons. My hope is that they hatch before the newspaper rots. The newspaper is showing signs of decay and won’t be able to hold the weight of the contents for much longer. Added 1 pound of food. When I say 385 pounds of food, I am also adding the weight of the worms and unfinished VC from the other bins. I really don’t know how many worms are in the OSCR. Stuff that I know is actually food weighs 230 pounds.

*[EDITORS NOTE]: I asked Mark for clarification on this “385 lb” number (since he had reported 249 lb of food waste added as of the time of this posting). Here is what he said: “The 385 pound includes the unfinished VC and worms. That is the total weight of the contents at that time. Remember I don’t want that newspaper to rupture too soon. So, the 385 pounds in the force downwards on the suspension cables.”


The newspaper is starting to breach. I put some containers under the ruptured spots to catch what has fallen. The stuff that had fallen had some worms in it that I tossed back in. I am hoping the bottom of the bin will be on the dry side so the worms will migrate up.


A major breach of the news paper. Finished VC and worms. I rescued 20 worms.

I also added 27 lbs. of pumpkin. I feel the bin is way overfed. I added 12 lbs of food yesterday. I turned on the fan and put tubs of water soaked manure in the harvest chamber. The tubs will catch the worms so they won’t dry out and die.

I was digging around the perimeter and found gobs of worms. I dug them out and put them on top. I then shoved cardboard down the sides to push the worms and food towards the middle.


I seem to have one spot 12 inches by 12 inches that is pushing 90 degrees F. I noticed this yesterday. I have trying the forced air to cool it off but, I want to go to bed so I just poured a quart of water on that spot. The newspaper has significant breaches in several spots, I am not rescuing as many worms as I have done before.

Just so you know, I will be creating a page on the site dedicated to Mark’s OSCR project where you will find links to his blog posts and other related information. Mark also suggested that I add some sort of running tally of the amount of food he has added – I thought this was a really cool idea, and will be adding something in the sidebar.

The next two videos feature tours of Mark’s system – first he shows us the view from the harvesting chamber, then he shows us the view from above, and takes us through a typical feeding session.

Stay tuned – very interesting stuff!

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Mark’s OSCR Videos – Part II

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Nutrient Loss From Worm Food


    • Andrew
    • November 10, 2009

    Mark, that is an amazing amount of food going in there. Of course it’s impossible to account for evaporation, but the water you add also adds to the overall weight pressing down on the cables & newspaper at the bottom. Roughly how deep is are the contents now compared to when you started? My flow through is tiny compared to your OSCR, but despite adding quite a bit of food stock to the bin, the level of compost has only risen maybe 1″ in one month.

    Keep up the good work!

    Andrew in Berkeley 🙂

  1. Andrew,
    When you say compost, are you talking about the working area (where the worms are) of your bin or the harvest area? My bin will stay about 16 inches deep in the working area.

  2. Good stuff!
    I sure appreciate Both of you (Bentley and Mark) for providing the info and hands on experience for the rest of us wormers.
    Thanks and keep up the good work!

    • Andrew
    • November 11, 2009

    Yes, the working area – all the material above the cables/grating. So that stays at 16″ depth even though you’ve put in all the food & additional bedding? Similar to my small flow through. It’s like a magic trick where you keep pouring something into a cup and it never overflows. Obviously in the case of the worm bins the material compresses as the worms work their magic, but it’s still interesting to observe. I mean in your case it’s hundreds of pounds!

  3. Andrew,
    Yes that is correct. One of the goals of this bin is to reduce the “trash” by 90%. The worms will hopefully process all but 10% of the organic waste.

    • Andrew
    • November 11, 2009

    I did not realize it was that much of a weight reduction. I’m slowly reading “Manual of On-Farm Vermicomposting and Vermiculture” By Glenn Munroe and found this:

    “In general, outputs from vermicomposting processes can vary from about 10% to closer to 50% of the original weight of the inputs. This will vary with the nature of the inputs and the system used. The greater the proportion of high-C inputs to high-N inputs, the greater will be the weight of final output as a proportion of input weight.”

    It sounds like you could adjust the food stock depending on whether your goal is to maximize “trash” reduction or to maximize vermicompost production. I think I’ll just throw in what I have and take what comes out…at least for now. I actually prefer more VC, but won’t try any complicated manipulation of food stock in order to achieve that goal.

    • Bentley
    • November 12, 2009

    ANDREW – your mention of being from Berkeley reminded me of one of my earliest introductions to the OSCR bin. There is a really cool article in one of the older editions of ‘Worm Digest’ – I believe it was actually called “Berkeley Worms”. It discussed a really cool vermicomposting project that some students at Berkeley set up. What’s great is that it looks like they are still at it – check out the website (I’ve linked to the page showing the OSCRs – which they have referred to as ‘Vermitopias’):


    • Andrew
    • November 12, 2009

    Bentley, the Berkeley group has morphed a bit since they built the Vermitopias, but they are definitely still composting with worms. They are now called Bay Worms and are where I bought my worms in the “compost ecosystem”. We had talked about this in one of your earlier blog posts. I didn’t think to ask to see the Vermitopias. If you go the 2nd link below you can read that they’ve upgraded the design to use metal frames.

    I’ll ask to see the Vermitopias when I visit them again. I’d promised them milkweed seedlings to attract Monarch butterflies to their community garden, so I’ll stop by the next time I’m in the area.

    Here are links to the current group:

    • Bentley
    • November 12, 2009

    Thanks for the info, Andrew – and apologies for not remembering our earlier conversation about this (so many vermi-things floating around in my head its tough to keep everything straight – haha).

    I’d be interested to get your thoughts on the Vermitopias if you do happen to make it out there for a visit.

    • Andrew
    • November 13, 2009

    No apologies needed, Bentley. You didn’t forget anything. We only talked about the “compost ecosystem”. I didn’t mention Berkeley or Vermitopias before. If I were writing as much as you, I’d be going crazy. It’s good you’ve got Mark to help out a bit. Excellent work!

    • James
    • July 18, 2010

    I am wondering if the reason the bin first went up to 90 when the fan went on could have from increased oxygen and thus more activity for the aerobic bacteria inside of the box.

  4. Hi James,
    I think you are correct. Those fluctuations of temps were a part of the set up phase of this bin and the learning curve. I am happy to report that this type of bin is my personal choice when it comes to vermicomposting.

  5. Mark I like your style of explaining your system. I did place an avocodo in some finished non worm compost weeks ago. Put the quart size carton in the basement window forgot all about it. Watched your video and ran down to check. It had sprouted. So I put it in my worm bin. Maybe if it grows some more I will trans plant it into a 5 gallon bucket. I don’t like avocodos and neither does my husband but I will see if it grows anyway. Find some one that loves avocodo’s and give it to them.
    Will you be using your VC in gardens. I sure hope you post videos of how your garden grows if so.

    • Brandon
    • March 25, 2020

    I wonder if it would be possible to post this video series up again.
    I’ve had the plans to build an OSCR compost system for a while, but I’m have trouble following the pictures in the blueprints. It would be amazing and inspiring to see one in operation and I think it would be helpful just to see the final product for my understanding of the design.
    There are not a lot of pictures out there.

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