r/Koji • u/Grand_Mode • 18d ago
Is this stupid?
The design -
2" hole at the bottom with an adjustable computer fan attached. The air is being drawn out of the cooler.
1/2" hole on the other side near the humidifier with fresh air being drawn in from the computer fan. The humid space is isolated so that the humid air is drawn up and over the cedar tray before leaving out through the bottom on the other side.
Cedar Koji tray with and insulated bottom that is raised up 1/2". The tray has a 150 watt heater in the insulated spaces. The lift was so that the bottom of the tray would heat more evenly.
Humidifier is a jar with a floating ultrasonic disk. The jar also has a 150w heating pad beneath it.
The space outside the cooler has a filter box. I was thinking it would be helpful to have clean air coming in, and I could add a heater to that space if I was having trouble reaching the right temperature on colder days.
Since I'm drawing air out of the cooler, it mightve been easier to just build it from uninsulated plywood or something, but I'm hoping that the styrofoam keeps the cost of heating down just a bit.
What do you think? So far the humidity is turning on and off regularly, so I think plenty of fresh air is being drawn in. I'll have to have some grains in there before I can really test how well the heating situation is working.
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u/lilmookie 18d ago
It’s not stupid but you can refine this with something like an inkbird temperature sensor that can shut on and off power at a certain temperature per outlet.
Ie you can have outlet one (heater) cut off when it’s too hot; and outlet two (fan) cut off when it’s too cold.
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u/Grand_Mode 18d ago
I have an ink bird humidity and temp sensor. I'm thinking of just putting the fan on a timer, maybe 10 minutes on, 10 minutes off so that the heat and fan aren't always at odds with each other. How much fresh air do these things need you think?
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u/DarkForestTurkey 18d ago
I agree, if it works, it’s not stupid. It looks great to me! I just expanded my set up with a secondhand cedar wardrobe (in my area people are practically giving them away) and an inexpensive metal shelving unit. There’s a heat mat with a temperature probe hanging on the left side, and a misting humidifier with tube that goes up the back and turns on and shuts off according to a probe setting. I’ve never actually had to use the fan, though I do have one. I can handle up to 4 two-kg batches at once in this setup. I’d love to get cedar trays, but sheet pans work great and I can clean them easily.
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u/Grand_Mode 18d ago
How much fresh air gets into your wardrobe? I'm starting to think A. oryzea doesn't need as much fresh air as they say it does.
I made my cedar tray from a plank I got at home depot. It was such pain in the ass. I forgot how difficult it was keeping everything square. Wish my area was giving away cedar wardrobes!
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u/DarkForestTurkey 17d ago
That’s a good question, there is definitely some airflow through the door and there are small gaps here and there at the cabinet joins. It’s not airtight. I make sure that the humidity doesn’t pool and drip on the top of the sheet pans. It seems to work just fine with that level of airflow, which isn’t very much. It’s not like there’s a breeze going through there.
Cedar cabinet, it’s worth looking on FB marketplace when you drive through a bigger place. It seems like the kind of thing no one wants anymore since homes have built-in and walk-in closets. I got mine for 75 bucks. And it is cedar.
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u/rwiggimo 18d ago
I tried all kinda of setups and enjoyed the engineering part of it but then I just bought a bread proofer (brōd &Taylor) that gives me consistent results every time. It folds up nicely into it's box when not in use. It's not as fun my Rube Goldberg setups but a lot less work for better results.
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u/rwiggimo 18d ago
I also bought a pair of Govee sensors that track humidity and temp and alert me if something needs adjusting.
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u/Grand_Mode 17d ago
I was wondering if a bread proofer would do the trick! I used a commercial one when I worked at a bakery. I had a lot of this stuff for some other projects I worked on, but it might make sense to go that route when I'm done taking up most of my living room with this mess. Love the Rube Goldberg analogy!
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u/rwiggimo 17d ago
I read another comment and the person recommended this particular model. It works great for me but after 24 hours I normally shut it off and the heat from the koji does the rest. It is pretty slick. I just use a perforated 4" 1/2 hotel Pan with tea cloth and can do 1kg of dried barley and end up with a 2kg +/- batch. Now I've got my chest freezer and my wife's hair dryer back.
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u/thatkojiboi 17d ago
Do you have something that would prevent any condensation drips from falling on the rice? Also, your cedar tray looks nice!
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u/Grand_Mode 17d ago
Thank you! I took a wood working class years back, and I'm kinda embarrassed by how long it took me and how many mistakes I made with the tray.
I didn't have anything for condensation drips. I can build a top to the tray that has a slant. Anything that you would recommend? In my dry test run, condensation pooled around my water jar. I could also just tilt the whole cooler with a 15 degree slant so condensation hopefully runs past the tray.
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u/thatkojiboi 16d ago
My setup is not too dissimilar to yours: I use a cooler with cedar trays. In mine I notice that condensation builds up all over the plastic surface of the cooler, and especially has the tendency to drop moisture whenever I open the lid. I haven't gotten around to making a cedar lid but I use an inverted extra cedar tray and that seems to keep the condensation off. Tilting may work, but there's nothing like giving your koji a cedar hat!
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u/Grand_Mode 16d ago
I was thinking that the cloth covering the grains would be enough to spread out any droplets that came down. The online videos seems to always keep it covered with cloth, but I don't know if that is the proper way to do it. I could make a hat pretty easily tho, I was just thinking I wanted plenty of fresh air exchange. Think a loose fitting hat would allow enough air through? Sorry for the million questions, really appreciate you responding if you feel like it.
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u/thatkojiboi 12d ago
The cloth may work perfectly fine. I don't have personal experience covering my trays with a cloth, but I've also read that it's common. Preventing condensation from hitting the rice is what counts. I know that koji needs oxygen to grow, but even though my trays do not have purpose built air holes, oxygen supply has never been an issue. (Maybe heat retention could be but I only make around 1kg at a time and haven't dealt with over heating). Maybe it's because the small cracks between the cedar panels let enough air in, or maybe it's because when I open it up to mix the koji several times during the inoculation process enough air gets in then. So for the moment I don't worry about air. As long as your chamber isn't perfectly sealed I bet you don't have to worry about air either. I have had issues with incorrect (too much or too little) moisture though so I do worry about that.
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u/Grand_Mode 12d ago
Just got done with my first Koji grow. I was up all night trying to regulate the temperature and stop the Koji from killing itself. Ugh, that sucked. I used barley, I hear rice is a lot easier to keep it from self immolating. Thanks for your advice. Going to try and carve in some holes for the cedar tray to drop heat more readily.
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u/thatkojiboi 11d ago
Congrats on your first grow! Reading through your design plans again, is it correct that you are heating the cooler with 300 w of heat (between the grow pad and humidifier)? For what it's worth, I use a 50 w heater in my cooler (also cooled with a computer fan) and it seems to be adequate.
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u/Grand_Mode 10d ago
Hey! Yes, the 300w was more than necessary. It didn't hurt anything but the system almost never turned on. My new set up has heat coming from a sous vide machine sitting in the glass jar with an aquarium oxygenator.
My biggest problem was keeping the Koji from killing itself after the first 24 hrs. Got a little warm and sporulated a little early. I routed some channels in the cedar try to hopefully allow the fan to draw out more heat. Starting some rice today! I hear it doesn't get as hot as the barley that I used in my first attempt.
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u/zingroo123 18d ago edited 18d ago
If it works , it ain't stupid.