18"x72" Plastic rack from home depot. Rack cover with clear plastic front from Amazon. Humidifier. 4" crappy booster fan and short length of 4" hose.
The fan and humidifier are controlled by a Sonoff 4Ch reflashed with EasyEsp. Timing is set by some simple rules.
Intake fan runs for 45 seconds. Humidifier runs for 300 seconds. 10 minutes later the humidifier runs for 60 seconds, 10 minutes after that the cycle repeats or something like that. The exact times vary but basically what you are doing is exchanging air as needed and keeping humidity levels up. The humidifier has a tube which runs up to the top level and the mist drifts down. I wound up putting in some cardboard to slow the air flow. How often you run fans and humidity depends on the season and how much is loaded in the fruiter but there is what seems to be a pretty big margin for error.
Currently I have King Oyster and Lions Mane growing. The Lions Mane is pretty sensitive to humidity and if you are screwing up you find out fast. It has been doing pretty well and gets toothy although not very big because it's in a quart jar.
There are some improvements. First would be to build a humidifier out of ultrasonic misters and a 5 gallon bucket and run a manifold with multiple distribution lines. As it is I refill the tank about twice a week but big humidifier and you could probably get better results. It would also not take up space within the chamber. It could use a couple led shop lights on the outside also to keep light levels up. Total parts cost, maybe $150. Assembly time, 30 minutes.
I tried hooking up a humidity and temperature sensor and controlling humidity via a sensor. Pure stupidity. No need to do that, just crank fresh air through and keep humidity levels up. I kind of suspect mushrooms prefer cycling humidity just a bit so they have a chance to dry out. Condensation on mushrooms is bad.
This would probably work for little brown socially unacceptable mushrooms if you happen to live in one of the free states that no longer outlaw them. Ironic that you can grow mushrooms which cause liver failure and horrible death and there ain't no law against that.
Measuring humidity and trying to run a humidifier accordingly sounds like a good idea but I recommend not going there unless you are spending big bucks on fancy meters that don't turn to shit in 98% humidity. The Sonoff is connected to the wifi, changing the rules to increase humidity or air flow is trivial and quick.
I also use a Sonoff hooked up to a one wire temp sensor and heater for the incubator.
EasyESP rules are pretty cool. The nice thing is they tend to be very reliable as opposed to controlling it with MQTT or HTTP. If you must turn things on and off remotely I recommend using a combination of rules and MQTT or HTTP. Turn the device on with MQTT and initiate a countdown timer which turns the device off. That way if your wifi or server goes down you don't kill shit. Always assume Gyna Shit Break, make sure things don't burn down, die, explode when it does.
