What is and how to make a Bulk or Monotub | EDADEA

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Monotub or Bulk involves growing mushrooms in a plastic box, bag or modified container.
By adjusting this household staple, growers can create the ideal microclimate that mushrooms need to grow.

A Monotub keeps humidity levels high, but has air holes that allow for proper gas exchange.  A substrate lines the base of the monotube and contains all the nutrients the fungi need to grow properly.
The mycelium will quickly colonise the entire substrate and a forest of small fruiting bodies will soon emerge.  This technique outperforms any other home method when it comes to production. In addition, monotub or bulk allows growers to concentrate all their efforts on a single structure, in comparison, tinkering with separate mycelium loaves and culture chambers requires considerably more effort.
Overall, monotub is easy, affordable and simple, as long as minimum hygiene and cleanliness standards are met.

To build your own bulk, you will need the following items:

-Cutter, knife or scissors.
-Absorbent paper/cooking paper.
-Plastic box with lid (25-35 litres, the one you see in the pictures is 25 litres and measures 36 x 42 x 35 cm).
-100% colonised granules of your favourite variety.
-Coconut fibre or Horsehair (Sterilised).
-Vermiculite (Sterilised).
-Bag of rubbish (Optional).
-Alcohol 70% in atomizer (recommended) (70% alcohol of 96 degrees and 30% water) it is necessary to reduce the alcohol because pure alcohol evaporates before killing the bacteria, Lysol, Sanytol, etc... would also be valid.
-10 volumes of hydrogen peroxide in a spray bottle (normal pharmacy water).
-Packing tape or similar.
-Laminar flow hood or similar (highly recommended).
-Microporous tape or aquarium bead.

More or less in the middle of the 25 litre plastic box we will make two holes in each of the two longest sides of the box, you can also make a hole in each of the 4 sides of the box, (both options are valid) of about 3-4 centimetres in diameter, if the táper is bigger you will have to make more holes or make them bigger.
The best way is to use a drill with a drill bit or a crown of the size, you can also use a cutter by heating it, be careful because the box could break if you make too much force.
With aluminium tape or any other opaque tape (I recommend strong American tape, so when we wash the plastic box for future bulk, it won't peel off), we cover the bottom part and between 8-10 centimetres on the bottom and sides (as far as the mixture with the grain and the substrate reaches), This is to prevent light from entering from below and from the sides so that all the mushrooms come out from the top, as if they were to come out from below they could rot and contaminate the whole crop. You can avoid this by using a rubbish bag inside the box and pouring the substrate inside, but I do not recommend it, as putting a bag or anything else inside the box will increase the chances of contaminating your bulk.

We recommend to use equal amounts of Grain/Fibre or Compost/Vermiculite and you could even add a little more grain than the other elements, as grain contains more nutrients needed for fungal growth.

Recommended mixes:
Mix 1.- This mix is the most commonly used for most varieties and is the one we sell.
1 part colonised grain
1 part vermiculite
1 part coconut fibre

Mixture 2
1 part colonised grain
1 part vermiculite
½ part coconut fibre and ½ part horse manure

Not all mushrooms feed on the same things, some varieties mix 1 would be perfect, but other varieties would need mix 2 for their perfect development, you can also substitute horse manure for cow manure (never fresh either).

It is very important that you do the work in a closed place, without air currents, animals or anything that can bring any contaminant to the crop, the slightest breeze can ruin your crop.

If you are not going to start the bulk as soon as you receive the mycelium, you can store it for a few days in the fridge at 4°C. When you decide to start the bulk, leave the colonised mycelium bag for a day or two at room temperature before making the bulk. When you decide to start the bulk, leave the bag of colonised mycelium for a day or two at room temperature before making the bulk so that the mycelium is activated, the colonisation of the substrate will be faster, if you do it just out of the fridge it takes longer to start colonising the substrate, the time difference is not much but as it is a sterile substrate the bacteria will enter it and the faster the mycelium colonises, the stronger it will be against them.

The first thing to do is to select where to make the mixture, we can mix directly in the fruiting box or mix in a smaller box, this will depend on the heating technique you use.
If you use the technique of heating with a water heater, (fish tank heaters) in a bottle, you will have to make the bulk in a smaller box that fits inside a larger one.
If you are going to heat with a heating blanket outside the box or in a temperature controlled room, do the bulk in the 25/35 litre box, I recommend the 25 litre box, as there is less risk of contamination as there is less air inside the box.
Cover the holes in the box with packing tape or similar, disinfect the entire work area, as well as your hands, gloves, arms and instruments with air atomised with 70% alcohol or some other disinfectant.
Spray the box and lid with alcohol, inside and out, and let the alcohol act for a couple of minutes.
Wipe the box and lid thoroughly with absorbent paper. Spray a little hydrogen peroxide on the inside of the box.
Disinfect with alcohol every utensil you are going to use, as well as the mycelium and substrate bags.

Take the bag of mycelium and crumble the grain into the bag before opening it, so that the grain is better distributed with the substrate and thus a better and faster colonisation.

Take the already sterilised substrate moistened to the correct point and add it to the monotube, the correct humidity is when a few drops of water fall by squeezing the substrate with your hand.

Then open the mycelium bag (sterilise with the flame of a lighter the cutter or scissors to open the mycelium bag and the substrate bag, you can also clean them with alcohol).

Pour the colonised grain on top of the substrate and with a previously disinfected spoon or fork, move the mixture well so that the grain mixes homogeneously with the substrate, when it is well mixed crush it a little with the previously disinfected spoon or fork so that it is a little compacted, not too much, you can also hit the box gently against the table so that the substrate is compacted a little.

Pour a little hydrogen peroxide over the substrate and on the walls and lid of the box.

Now put packing tape around the lid to seal the taper so that no bacteria will enter and no moisture will be lost during the colonisation period, leave the taper in the dark at a temperature of 22-25 degrees (at 22 degrees it colonises more slowly but the higher the temperature the more likely it is to become contaminated).

Keep in mind that inside the monotube it will be 1-3 degrees warmer due to the heat produced by the mycelium during colonisation (you can leave one side of the box unsealed to avoid excessive condensation if you have high temperatures).

OPTIONAL (but highly recommended):

Casing Layer

After 8-12 days of colonisation (depending on temperature and species), when you see that the substrate is almost completely colonised,

add a layer of sterilised, moist vermiculite of 0.5 cm or so covering the entire top layer of mycelium,

(this can avoid contamination, as well as providing extra humidity and stimulating the growth of mushrooms all over the surface, if you don't put the casing layer the mushrooms will come out of the wettest place, which will be on the sides of the bulk and you will not have an optimum yield.

In addition, if a small puddle of water has formed on the mycelium due to condensation on the walls during colonisation, the vermiculite will absorb this water and prevent contamination.

Spray a little hydrogen peroxide on top of the vermiculite.

If you have touched the edges of the taper with your arms or anything else, wipe the edges of the box with an alcohol wipe before closing it, also pour a little hydrogen peroxide on the lid before putting it on, not too much, as the humidity could rise too high and become contaminated by waterlogging.

Leave it in the dark for another 2-4 days until you see that it is already colonising the vermiculite.

Then place it in a period of 12 hours of light and 12 hours of darkness if you use artificial light.
When you see the first mushrooms start to appear, remove the tape from the holes and put perlon or microporous tape to improve gas exchange and prevent pollutants from entering the culture.

Microporous tape prevents the entry of bacteria but the gas exchange is very low so you will have to ventilate more.
Perlon does not prevent the entry of all contaminants but the gas exchange is higher so you will have to ventilate less.

Ventilate the box several times a day and if the humidity is low, spray with tap water mixed with a little hydrogen peroxide, the humidity should be at 85% or so. Never pour the water over the mushrooms, spray the walls of the taper.

There are several reasons why mushrooms can be contaminated, the most important is because they are grown artificially. This means that in nature there is a balance between bacteria, fungi and other organisms and micro-organisms, but to produce magic mushrooms indoors it is necessary to prepare the medium, which causes the biological imbalance, and with it the possible infections.
When we sterilise a substrate we leave it clean of contaminants, but the absence of other agents means that the first one to enter the medium will flourish without competition, something that does not happen in nature thanks to the balance between species.
Pollution can come through the air, water, the tools we use, our clothes, etc....
Any external agent that enters the culture medium can pose a threat, so it is essential to carry out adequate disinfection and sterilisation.

Hygiene and care when handling mushroom bread is crucial, as well as keeping it away from pets and other contaminating vectors.
Contamination is always caused by poor disinfection or sterilisation of the growing medium and utensils. We can also have it due to poor handling or we can even be the ones who act as a bridge to transmit infections. Extreme cleanliness is always recommended when starting, the reward will be worth it.

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