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Thread: How to build a ShotGun Fruiting Chamber (SGFC) for mushrooms

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    Default How to build a ShotGun Fruiting Chamber (SGFC) for mushrooms

    This guide is a work in progress. I'll keep updating as my grow progresses to show you guys how I set mine up.

    Once your mycelium is colonized you need to start fruiting it to get some mushrooms. To do this we have a few options for fruiting chambers. The one in this guide is the staple of brown rice cake growers, and is very simple....but building it is time consuming. Prepare for this to take about 2 hours. You've never drilled so many holes in your life I bet. You've been warned! lol

    For mushrooms to fruit you want to introduce them to indirect 6500k light (only a 10w CFL) and a lower RH. To accomplish that we use a clear 66qt Sterilite storage bin....with a lot of holes.

    The basic principle is easy. You drill 1/4" holes all around the bin every 2" in a grid pattern...don't forget the corners! Do all 6 sides (4 sides + top & bottom). I marked mine first so I could keep it looking neat and presentable when it is finished. The size and pattern of the holes is the most important part!! This method is figured out down to a science! Don't forget to clean up any burrs left behind from drilling the holes. We don't want sharp edges to rip our mushroom caps apart. We also want to ensure the chamber is getting proper FAE, so the drill holes need to be cleaned out good. Just be careful you don't make them any bigger.

    Next, we put wet perlite in the bottom few inches..3-4" is good. You'll get some runoff from the perlite, so have a drip pan ready underneath. You won't need to leave it there forever, but it's a good idea to have it during setup. You must use perlite. Don't substitute this for any other material.

    The idea here is to have constant fresh air exchange (FAE) while maintaining a fairly high humidity, albeit lower than during colonization. The holes in the bottom of the tub serve a very important role in the humidity. The fruiting chamber must remain elevated at all times to allow air flow under the bottom. You'll want 3" clearance, minimum. This fresh air flow underneath creates ventilation up and through the perlite, which in turn evaporates some of the water stored in the perlite. This creates humidity and the holes all around the chamber ventilate it enough so there is constant fresh air. The holes should be plugged up as little as possible. Covering holes has the opposite effect you would LOWERS humidity. In order to maintain a proper balance between FAE and humidity, you must ensure your holes are correctly spaced as well as sized.

    Ok, on to the cakes/bricks. If you've built your SGFC to spec, you should be able to fit 2 standard sized bags of perlite in the bottom (for a 66qt tub, the same size mine is) and there will be a row of holes just barely above the perlite surface. If not, it's ok, but this is the ideal configuration to allow proper gas exchanges. If your tub isn't the same size, adjust accordingly. Remember, mushrooms are not like the plants we are used to. They breathe oxygen and emit co2 like mammals. Gas exchange is very important, because to trigger the cakes to fruit, you want to increase FAE from the level the cakes were used to in colonization. FAE increase, as well as the act of moisture collecting and evaporating are the main two triggers that tell the cake it's time to start producing mushies. In other words, triggering your mycelium to fruit is almost entirely dependant on the amount of FAE your SGFC gets.

    This part of the guide is very straight-forward. If you've gotten this far you can pat yourself on the back, because you're on the home stretch...nothing is guaranteed yet, but the real nail-biting part is over and you can stop worrying about contamination (mostly). Fruiting is a fairly dirty job. You can safely handle your cakes, etc without worry from here out. Obviously you'll want to wash your hands and try to not breathe directly into the SGFC if at all possible, since your breath will carry far more germs than any of us are aware of. You don't have to be paranoid, though. Sterility is no longer of the utmost importance once you've reached 100% colonization.

    When you're ready, just pop your cakes out of the jar (or remove the brick from the bag). Since aluminum foil is heated to extreme temperatures in a sterile environment when it's made, it's a good material to use. Tear the first foot of foil off the roll and either throw it out or save it for don't want to use the first foot for this. Then tear off a small square, place it on top of the (pre-wetted and washed) perlite and gently place your cake (or brick) on top. If you used bags to form a brick like mine, you can copy my method and dig out a small hole so your brick doesn't come quite so close to the top of the SGFC. Remember, the fruits will grow out and up, including from the be sure you leave head-room for them to grow! DO NOT wipe your foil with iso alcohol!!! It's already sterile straight off the roll and doing so could compromise its sterility.

    This part is very important!! Read carefully, please:
    Before pinning it is very important you mist your cake/bricks several times a day. DO NOT mist if the moisture hasn't evaporated from the previous misting!! Remember...the moisture evaporation/re-condensation is what triggers pinning, so be sure that moisture has evaporated before misting again. Most people end up mistng approximately 6 times daily. DO NOT get yourself on a misting schedule!! Just watch your cakes/bricks. When they stop glistening from moisture, it's time to mist again, but not before! It is better to under-mist than over-mist, similarly to how underwatering a MJ plant is better than overwatering. Spray the cakes, perlite, all sides, and the lid. Many people like to also use the lid to fan the SGFC slightly to ensure all the co2 the cakes emit has dissipated before replacing the lid. After misting the lid it's a good idea to give the lid a shake so you can be sure no droplets collect and drip onto your cakes like rain.

    After pins form you can pull back on misting...cut the amount of times daily in half. NEVER spray your mushrooms/pins directly. This could cause them to rot or abort.

    Pins take about 5-10 days, on average to form, and 3-7 days later your mushrooms will have reached harvest maturity. Be sure you harvest them just after the first veils start to break or they could drop spores and your cakes will mold. If you see purple/blue on your cakes you waited too long and your cake is probably not going to flush again.

    The following is a review of everything discussed above, just with pics to give you a visual idea of what I'm talking about.

    Step 1:
    measure and mark a 2" grid pattern on all 4 sides, top and bottom. Don't forget near the handles, corners, edges, the top near the rim....don't leave any spots out.

    Step 2:
    Drill 1/4" holes on all your marks. Make sure your drill bit is the right size. This is critical to your fruiting chamber's success!
    I'd recommend you wrap something nice & comfortable around your drill. You're going to be using it a LONG time for this project. I got a blister and it popped while doing this.

    Step 3:
    If you look closely you can see all those sharp points poking in from where you drilled. Those need to come off. The easiest way is to use scissors. Open them all the way, stick one blade into the drill hole from the opposite side from which you drilled the hole, and twist a few times. That burr should pop right off and leave a nice smooth hole. Be careful not to make the holes any bigger...that would be counter-productive. Do every hole on all 6 sides. See why this takes so long?

    Here's our nice finished Shotgun Fruiting Chamber...minus the perlite and colonized cakes

    Fill your SGFC 3-4" with wet perlite, poke any clogged holes with a pen so you get proper FAE, and place your cake/brick on a fresh piece of foil.

    Mist and fan your SGFC, perlite and cakes several times a day to induce pins

    Once your mushrooms start taking a familiar shape, you'll most likely see a veil connecting the underside of the cap to the stem. Pay close attention to this. You'll notice in the next few pics how they have changed shape drastically. In the second and third pics the veil has broken, the gills under the cap are exposed, and they are ready to drop spores. You may even notice a couple spots of the perlite have turned purple. Those are spores, and your cake is ready. Harvest the whole cake. Don't leave any pins or mushrooms. Take a nice sharp knife, and carefully run it along the surface of the cake to cut any clusters or pins flush 2ith the cake. don't twist! you'll do damage.

    Dry them, use them fresh, or add these to your extract or cooking recipe. These are ready immediately after cutting from the cake, and best used while as fresh as possible, as drying degrades the actives slightly. Enjoy!!!

    Your cakes can be reused for another 2 or 3 cycles, as well!! You'll get slightly diminished yield with each flush cycle, but still....more mushies!! Just dunk your cake totally submerged, with something clean holding it down underwater. i like to use a big mixing bowl and a heavy plate. Make sure they're totally under part of the cake can be exposed to air or it will rot!! Just use tap water...never distilled.

    After 24 hours, roll in dry vermiculite, and place on a fresh piece of foil in the SGFC to fruit once more. When it changes color, smells foul, or molds, it's spent and can't be saved. Throw it out away from your jars.

    Hope this helps! If anyone has any questions, please ask!! It's not anywhere near as intimidating as most people think, and once you do your first run, you've got it!!
    Last edited by Lightyear; 4th March 2017 at 02:58 PM.
    Medicine in the hands of a fool is poison,
    just as poison becomes medicine in the hands of the wise.
    ~ Casanova

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