MYCOLOGOS Mini Martha v2

Supported number of grow kits: 2–10,
depending on the size of plastic tote used.
Approximate cost: $50–150
Construction time: 30–60 minutes

This small automated fruiting environment can accommodate multiple grow kits, depending on the size of the plastic tote used. The cost of this design varies based on tool investment options.

Materials:

Tall plastic tote – The ideal tote for this system is at least 20 inches high (to accommodate for the height of the humidifier shown) and transparent. The width and length of the tote are up to you, though longer and wider totes will hold more kits.
Aromacare Cool Mist Humidifier – This humidifier is suggested as it has a small footprint, can be filled from the top, and will work with the minute timers listed below (unlike some digital humidifiers, which need to be turned on manually prior to each cycle). You can use any ultrasonic or cool mist humidifier, you just need to ensure that you can channel its mist somehow.
(1) Computer fan with built in plug
(1) 3-foot segment of 1” PVC pipe
(1) 1” PVC threaded male adapter
(1) 1” PVC threaded female adapter
(1) 1” PVC elbow
(1) 1" PVC coupling
(2) 1.25" gasket
(4) 1.25” bolts and nuts (narrow enough to fit through the mounting holes in the computer fan).
(2) Minute timers
(1–3) Nylon mesh paint strainer bags
Micropore tape ( a.k.a. first aid tape)
Perlite
Loose weave filtering material used in air conditioners (e.g. this material)

Tools:

Measuring tape
Something to cut the PVC, such as a hand saw, a miter saw, sharp knife, or a PVC cutter. Most hardware stores will also cut PVC for free.
Electric drill driver and bit set
A means to cut circles in the tote plastic, such as:

A Hole saw set
Or a very sharp utility knife (but be careful to not crack the plastic!)

Step 1: Prepare the Tote

Drill four to ten 1/4” drainage holes in the lowest areas of the tote's bottom (or enough holes to ensure good drainage). Drill all holes slowly, to avoid cracking the (likely) brittle plastic of the tote.
Mark a line around the perimeter of the tote that is 3 inches from the bottom of the tote. Drill 1/4” holes along this line every 2 inches. These are for venting out excess carbon dioxide (CO2) produced by the mushrooms as they grow. Optionally, cover these holes with micropore (first aid) tape to keep insects out.
Using the 1.25” hole saw, drill out a hole on one of the short sides of the tote, approximately 17 inches (on center) from the bottom of the tote. This is where the humidifier will be connected.
Using the 3” hole saw, drill out a hole on one of the long sides of the tote, near the top of the tote. This is where a computer fan will be connected to bring in fresh air.

Step 2: Connect the fan

Tape the computer fan over the 3” hole, centering and squaring it where you would like it to be mounted. Using a 1/8” drill bit, drill a hole in the tote for each of the corners of the computer fan, using the fan’s holes as a guide.
Cut a piece of air filtering material to match the size of the computer fan (approximately 3” x 3”).
Mount the fan to the tote with the 1.25” bolts and corresponding nuts, sandwiching the filter material between the fan and the tote. Be sure to mount the fan so that the air blows into the tote, not out of it.
Plug the fan into one of the minute timers and set the timer to turn on for one minute every 10 minutes.

Step 3: Connect the humidifier

Cut two pieces of PVC. The size of these pieces will vary based on the size of your tote. You only need to them to be long enough to connect the humidifier as shown, ensuring the vertical piece is snug against the opening of the humidifier. Cut the pieces longer than you think you will need them to be and trim them down as needed until the fitment is just right.
Place a gasket on the 1” PVC threaded male connector and screw it through the 1.25” hole.
Place a gasket on the PVC connector's threads and then screw on the 1” PVC female connector, creating a “sandwich” of the gasket, tote wall, and gasket.
Connect the 1” PVC threaded male connector to the PVC elbow horizontally, then the elbow to the humidifier vertically using the pieces cut in step 3.1 and the 1" coupling. If cut properly, the coupling should be snug against the opening of the humidifier and not require any additional seals to send all of the mist into the tote. If you do experience some light leaking, you can wrap the bottom of the coupling in electrical tape, or seal it to the PVC with silicone.
Plug the humidifier into the second minute timer and set it to turn on based on the guidelines below.

Step 4: Prepare the bottom

Line the bottom of the tote with one or two paint strainer bags.
Cover these liners with 3 inches of perlite, or enough to fill up to 1/8" below the small ventilation holes along the bottom of the tote.
Place the Mini Martha over a water collecting towel or tray (such as a large baking tray, shallow tote, or small animal kennel tray).

Use and Maintenance

Place your new Mini Martha in an area with indirect sunlight or with a full spectrum light source (such as a high output 6000–6500K LED light). Waterproof LED lights can also be placed on the inside of the lid of the tote, creating a more self-contained system. Finally, place your grow kit(s) in the tote after they have been prepared for fruiting (as detailed in the instructions provided with each grow kit).

Turn on the humidifier until a light mist develops on the walls of the tote alongside light streaking down its walls. As the computer fan turns on every 10 minutes (so as to bring in the fresh oxygen that the mushrooms need), the humidity level will drop. Monitor your setup and adjust the humidifier’s timer to run for as long as is needed to maintain the mist level described. Within a day or two you should be able to determine the best setting for the humidifier’s timer and thereafter only need to adjust its setting as the seasons change and ambient humidity and temperature levels influence the fruiting environment.