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CO2control: essential for good results.

Micro perforation

Aeration of the substrate bags is essential to control the CO2 level in the substrate. The quality of the micro perforation is extremely important for optimal air exchange. Heat emission also plays an important role. With too large a diameter of the bag, the substrate soon becomes too hot, causing the mycelium to die off in the centre of the bag. Preference is given to hanging substrate bags. Excess water can flow away so anaerobic conditions are avoided. Competing moulds at the bottom of the bag are given much less chance to grow, because the conditions remain optimal for the cultivated mycelium.

Incubation room

Only the use of good bags will not be enough for a good result. The room conditions are just as important. Air exchange is only possible if the incubation room does not contain over 2500 ppm CO2. Air exchange of the bags takes place mainly through diffusion: air exchange based on different concentration levels. For example, if the CO2 concentration is 5000 ppm, the diffusion will be half as much compared to 2500 ppm. This results in a longer incubation period. The proper measurement of the CO2 in the air is therefore essential for a controlled growth of the mycelium in the substrate bags. The CO2 concentration raises quickly if the incubation room is filled during weeks. This causes a great delay in the growth of mycelium and, in the worst case, the mycelium is killed. Only CO2 controlled conditions will result in a constant incubation period. So measure the CO2...


Unintentionally, the first mistake is often made when the spawn is delivered. At the moment the spawn arrives, the temperature must be measured immediately. Warm spawn is already very active and produces a lot of CO2. This is soon too much CO2 for the built-in filters, causing the CO2 level to rise too far. Fast and refrigerated transport is therefore essential. Cool the spawn as soon as possible after delivery to decrees the activity of the mycelium. Spawn comes in bags with a filter. These filters provide just enough gas exchange for storage of the spawn at a low temperature (just above 0 °C). At higher temperatures, the activity of the mycelium soon increases and therefor also the CO2 production. The air permeability of the filters is not sufficient for this. So make sure that the stored bags do not touch each other for optimal cooling and never lay the bags on the filter. Especially Oyster Mushroom mycelium produces CO2 at low temperatures. The CO2 content in the refrigerator will therefore also rise, as a result of which the air exchange between gas in the bag and the air in the cooling will be reduced further and further. This makes the mycelium less and less powerful because it is "poisoned" by the CO2. Inoculation with this badley treated spawn will certainly cause problems. Growth of the mycelium in the substrate will be significantly slower, giving other fungi the chance to grow. Opening the cooling once daily, even if only for 10 seconds, ensures sufficient ventilation. Strange and unknown cultivation problems are often caused by this first mistake!