SGFC TEK: Build The Absolute Best Shotgun Fruiting Chamber for Mushrooms

Updated: Apr 14

In general a mushroom fruiting chamber is a container intended to keep a fruiting blocks hydrated while also providing air exchange and good evaporation from mushroom block surfaces.


This particular build is referred to as a shotgun fruiting chamber because the Sterlite tub looks as if it has been blasted from the side with a shotgun full of buckshot. When the shotgun fruiting chamber (SGFC) is made, the result is that the tub will be peppered with potentially hundreds of small Air-Exchange holes.


A shotgun fruiting chamber is a very easy build. While it may look similar to Monotub Tek it is very different in that Monotub tek is slightly more detailed to build. The simpler Shot gun fruiting chamber, described here, requires a little bit more skill to use than is required with the Monotub Tek.

Just like form defines function in Anatomy & Physiology, how we modify these Sterlite tubs determines what they can do for us. While the Monotub tek offers a non-complicated, automated Large capacity harvest potential from start to finish. The Shotgun Fruiting Chamber (SGFC) offers more experienced growers the opportunity to more precisely define the growing conditions. These modifications to growing conditions (Temperature / Air Exchange / Humidity, Etc. ) are most often performed by hand by the mycology expert in residence.


In Monotub Tek, substrate is allowed to colonize new grain, dung or hardwoods substrates with grain spawn for the largest flushes possible. Conversely The Shotgun Fruiting Chamber has fully colonized fruiting blocks or jars placed in it. The floor of the Shotgun Fruiting chamber has a thin 1/2" to 1" thick layer of damp perlite on the bottom of the container at the level of the Fresh-Air Exchange (FAE) Holes. Because the fruiting blocks entering a Shotgun Fruiting (SGFC) are fully colonized, the holes of a SGFC do not need to be covered with anything. While good to stock up on for other projects, no 3M Micropore tape is required for this one.

Required Materials to Build The Best Shotgun Fruiting Chamber


Step by Step Instructions Its best to try and follow these directions to the letter. Experienced growers are not often able to come up with innovative improvements to this method. While we are sure improvements are possible, following the tried and true method will provide you with the best results.


Step 1. Mark Out Shotgun Hole Locations Mark out a grid of sharpie marker dots evenly spaced every 2". This grid will need to cover all 6 sides of the Sterlite container.

Step 2. Melt Holes with Soldering Iron Use a soldering iron to gently melt the holes into the plastic at each of the black marker locations. A soldering iron works tremendously better than a drill and will not crack your Sterlite tote.

Step 3. Fill with Perlite Rinse the perlite in hot water to remove any hole clogging dust. Put a 3" layer of perlite down into the Sterlite tote.

Step 4. Put Just One Fruiting Block into the Shotgun Fruiting Chamber The Shotgun Fruiting Chamber should not be filled to capacity in order to promote the best circulation of air flow. If the chamber is filled to capacity it will impede the free movement of airflow which is a critical component to the functioning of the chamber.


It is necessary to place a hygrometer with probe into the chamber. This helps you tremendously in monitoring the parameters of the Shotgun Fruiting Chamber.

Step 5. Place your completed Shotgun Fruiting Chamber up on the small platform The Shotgun Fruiting Chamber must not be placed on the ground. This method requires fresh air flow to move around the myceliated brick on all sides.

Step 6: Be patient and check the hygrometer at least three times a day. Shotgun fruiting chambers require near constant attention multiple times every day in order to function with the intended success rate.

Spraying and Fanning You will need to mist with the spray bottle at least 3 times a day. more is better. Eventually you will get skilled enough to determine when to mist and when to fan depending on the visual condition of the fruiting block.


It is best to not spray the block directly. You want the droplets that do land directly onto the fruiting block to be microscopic in order to more freely evaporate. This evaporation reduces localized temperatures on the surface of the block. Do not allow the perlite to dry out. The perlite acts to ballast the humidity inside of the Shotgun Fruiting Chamber.

Mycelium does not require oxygen but mushrooms do require fresh air and oxygen. Oxygen helps a block determine when it is time to begin fruiting. Fan the block immediately after spraying around it in order to rarify the humidity, to dry out the air. This creates the situation where the micro water drops evaporate faster and in turn promote hyphal mass development (pinning)

To hand fan, literally remove lid and use it to fan fresh air into the inside of the chamber several times.

Lighting The Shotgun Fruiting Chamber (SGFC) prefers indirect lighting. The lighting tells the mycelium where to pin and then which direction to grow. Mushrooms do not utilize photosynthesis so increasing the intensity of the light will not increase the productivity of the system and will not increase the amount of mushroom fruiting bodies that are produced. Give the Chamber at least 6 hours of darkness in order to allow the block to rest in between growth spurts during daylight hours.




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