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Posted on Saturday, June 28, 2003 - 11:32 pm:Edit Post Quote Text Delete Post Print Post Move Post (Moderator/Admin Only)

ShroomGod's Humidifier Tek


Hello, fellow trippers! I want to share what I've discovered through playing around. First, I'll be right out in the open and say that I believe poor gas exchange is the number one reason people are experiencing oddly shaped mushrooms (ex. Very long-stemmed with a disproportionately small cap). I also think it is a BIG contributor of cobweb and green mold, both of which seem to plague many cultivators, both novice and experienced. I personally believe very-long-stemmed mushrooms grown in low-gas-exchange terrariums sometimes cause more stomach cramps, although I've never read such nor have strong supporting evidence.
In the famous book The Mushroom Cultivator, the appropriate gas exchange level for Cubensis is quoted at a minimum of 1 to 3 times per hour. Think about it! That means all the air in your terrarium, especially if it's cramped, should be displaced 1 to 3 times per hour! A lower level than this leads to disproportionate elongation of the stems. The humidifier is the key to proper gas exchange and humidity levels, so I compiled this page to compare some types of humidifiers. Below are some of the pros and cons, as I see them, of various humidifiers I've heard folks using around the Shroomery:

Ultrasonic Humidifier


The flowing mist looks awesome!
Plenty of gas exchange when they are actually on


Ultrasonic transducer is prone to failure
Creates a dense mist that quickly over saturates the casing. This implies a periodic operation thereby not providing constant gas exchange
Ultrasonic Fogger


The misty cloud on the terrarium floor looks awesome!

Ultrasonic transducer is prone to failure
Creates a dense mist that quickly over saturates the casing (periodic operation).
Takes up lots of terrarium space
No gas exchange
Wet Perlite Layer


Cheapest of all solutions
Does not over saturate the casing via mist

No gas exchange
Messy as hell
Perlite must be frequently cleaned or replaced
Aquarium Bubbler


Fairly inexpensive
Provides constant gas exchange, albeit somewhat limited per diaphragm
No mist or over saturation of casing
Easy to clean and maintain

Very noisy
Does not provide enough gas exchange to mimic a natural setting
And my favorite...

Cool Mist Humidifier Connected to a Garden Hose!


High, constant gas exchange mimicking a natural setting
No mist or over saturation of casing (if set up properly with adequate hosing length)

Some additional setup steps required
Some models do not turn off once they go dry making a potential drying hazard if the water goes too low
So, where do you find a cool mist humidifier? If you live in the US, most K-mart stores carry a small model by Kaz (Click here for a picture). This is what I use and it's perfect. I find that it can drive four hoses without a problem. Regardless of the brand, it should not have a wick inside! It should not have the word "evaporative" anywhere on the box either. Rather the inside should have a spinning disk surrounded by a circular splash comb. Here's how to set it up:

Purchase a small cool mist humidifier, a 5/8" (preferably 11/16th" if you can find it) drill bit, some duck tape, and the cheapest 5/8" inner diameter garden hose you can find.
Cover the original humidity output slot with duck tape.
Cut a length of hose (cut off the end attachments) at least 1.5 feet long but preferably longer. It must be long enough to connect the humidifier to your terrarium and allow the mist to hit the sides of the hose.
Drill a hole in the corner of the humidifier. Wiggle the drill around a bit to make it slightly larger if you could just find the 5/8" bit.
Using your body weight try to squeeze the hose in about 1/4 to 1/2 inch. It will be tight. You'll have to work with it as it won't push in easily.
Repeat steps 4 and 5 for one of the other three corners if you'd like an additional output. Some have reported that two outputs is the maximum number their humidifier can handle, and indeed, this is the largest number I have ever personally used.
Hook up the terrarium to the hose. The hose needs to be long and curvy enough to "de-mist" the output. On the other hand, I would not recommend vertical loops as they can collect water in them blocking the air passage. The hose should be laid such that any water drops that form on the inner walls of the hose run back down in to the humidifier. This is very important, especially in the first foot of hose, because if you don't lay the hose this way, water will drip in to your terrarium causing major problems! Just to be safe, place a small cup in the terrarium under the output of the hose.
Fill the humidifier's reservoir with water. I'd also recommend adding 1/8th to 1/4th cups 3% hydrogen peroxide (stuff at the drug store) per gallon water to keep it fresh.
Run 24/7.
If you need a 90° turn in to the top of your terrarium, I'd recommend 1/2" PVC elbow (about twenty cents). You can push in the garden hose to one end and the terrarium on the other. Some people might not have a drill. If that's your case, then I'd recommend you just cut the slot a little bigger and duck tape the hose to it. It'll be a lot messier, but it should work.
When I first read about using a cool mist humidifier, I read about using a 1" PVC tubing. That doesn't work well. For starters, PVC is rigid, hard to cut, and generally hard to deal with. Additionally, such a large tube allows free mist to reach the other end, which means you can't have the humidifier running constantly. That's the same problem one has with the ultrasonic humidifiers! Lastly, if you used more than two such tubes, you'd be running out of water really fast. The garden hose limits the output sufficiently so that given one tank water with one output, the tank should last several days without need for a refill (even in a dry room). Also, the relatively thin diameter of the garden hose and the turns run the mist against the walls before it reaches the output. A cool mist set up simply works GREAT!

To emphasize the point, I'm currently running such a humidifier with one output on some oyster elm mushrooms. These mushrooms will NOT grow using perlite or an aquarium bubbler since they require twice the gas exchange of Cubes. Yet using this set up, a single garden hose output provides plenty of gas exchange for two and a half square feet of cropping surface AND keeps humidity levels above 90% RH even when the air-conditioned room air is as dry as 25% RH!


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