Good ventilation is one of the most important factors for successful indoor cannabis cultivation. Without it, it will not be possible to get a high-quality and bountiful harvest. Even if the box is designed almost perfectly, but there was no room for a ventilation system, it will turn into a “gas chamber” where moisture collects, creating conditions for the prosperity of pathogenic microorganisms. Moreover, an unventilated greenhouse can create a huge number of problems for the gardener through its characteristic odor.
When designing ventilation in a grow room, growers follow the same principles as when building a grow box. At the heart of everything is the volume of the room and the number of plants. The higher these values are, the more efficient the system should be. Only with the constant renewal of the air inside the grow room will favorable conditions be created for the cultivation of cannabis. It will grow healthy and strong, which will inevitably lead to increased productivity and quality of the finished product.
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Ventilation system functions
The ventilation system in the grow room is designed to perform four important tasks:
Warm air removal. Excessive accumulation of heated air by the lighting equipment raises the temperature inside, and also leads to the accumulation of moisture. Cannabis feels good when the air humidity is in the range of 40-60%. All indoor growers try to adhere to this indicator, keeping it to a minimum during the flowering period.
Air renewal. Any plant needs carbon dioxide to carry out processes important for growth. The constant supply of fresh air allows the plant to breathe, increasing the CO2 concentration. Also, without proper air exchange, the pores on the leaves become clogged, blocking their ability to absorb oxygen and the already mentioned carbon dioxide, which leads to death. And since the leaves are needed by the plant to absorb light energy, then it begins to receive less of it, which leads to a decrease in performance indicators.
Cleaning the exhaust air from the smell of cannabis. The grow room accommodates a large number of cannabis bushes, which together emit a rich and pronounced cannabis aroma. It is difficult to convey all its intensity in words. Let’s just say that ten hemp bushes growing without a charcoal filter and hood will smell even in the yard and in most of the neighboring apartments.
Strengthening the stems. The constant air exchange inside the grow room creates an artificial wind that forces the plant to resist it. Developing in such conditions, it is forced to strengthen the stems and branches, making them stronger. It also stimulates the development of the root system. All this together has a positive effect on the yield of the bushes.
The device of the ventilation system of the growroom
When designing a ventilation system for a grow room, the volume of the room and the type of lighting equipment are taken into account. Based on these data, its required power and the most suitable design are determined. In general, an effective ventilation system consists of 5 basic elements. Some of them can be duplicated to provide an increase in power, some, on the contrary, may in some cases not be installed at all.
These elements are:
This is the most important element of the system. In its most primitive form, all ventilation consists only of it. The absence of a hood will not allow stagnant air to be removed.
The exhaust fan is always installed under the ceiling, since this is where all the heated air is collected. The power is selected depending on the volume of the grow room, so that it completely renews the air inside at least once every 2 hours. The required refresh time depends on the temperature inside. If HPS lamps are installed in the grow room, then this has to be done more often, if LED – less often.
In the first case, growers usually use either powerful industrial fans or connect HPS lamps to active cooling luminaires. One of these is CoolMaster 100. In this, the lamp is installed behind glass, which acts as a thermal barrier, keeping the air inside the structure. The luminaire housing has an inlet and outlet for connection to a ventilation system that ensures a constant air flow. As a result, heat is immediately discharged outside the growroom, without heating the air inside.
When installing LED luminaires in a grow room, growers usually get by with ordinary household fans. The thing is that during operation they emit much less heat, and some of them are equipped with their own cooling system. An excellent example is the Apollo 4 LED phytopanel. But such lamps outperform HPS not only due to lower heat transfer. They emit the most cannabis-friendly light spectra, which promotes more vigorous growth. They also distribute the luminous flux evenly over the surface, are easy to install and maintain. The only drawbacks are the price (although in recent years it has significantly decreased) and a slightly lower penetrating ability of the luminous flux, forcing to master the intricacies of defoliation.
A supply fan provides fresh air to the grow room. In small rooms, you can do without it, provided there is sufficient power of the exhaust fan, which creates a pressure difference inside the room. In this case, the flow of air will be carried out automatically through the technological holes, and any slots, in principle.
Typically, growers install a supply fan if:
A more efficient and faster renewal of indoor air is needed to create a favorable microclimate
The growroom is sealed and there is not enough fresh air
It is necessary to stabilize the low internal pressure due to the exhaust fan. This is especially true in cases where the walls of the grow room are made of fabric or elastic material, which is subjected to a “vacuum effect”, reducing the amount of free space inside.
When choosing a supply fan, it is necessary to be guided by the fact that its power must certainly be less than that of the exhaust fan. This parameter is determined taking into account the resistance coefficient of the charcoal filter. Otherwise, the latter will not be able to effectively purify the air due to the pressure drop.
Household built-in fans can be used to provide air flow in the grow room. They are installed just above the floor level so that cold air displaces hot air upward.
During the flowering period, hemp inflorescences begin to fill with terpenes – aromatic compounds that emit a rich smell. If the air from the grow room goes out without purification, then sooner or later it will attract unnecessary attention.
There are two options for the location of the carbon filter – at the outlet of the ventilation system, or inside the grow room itself. The number of adherents of both methods is approximately equal, but we recommend the second option. The fact is that in this case the fan will work for suction and not for blowing out, which will relieve it of the need to overcome atmospheric pressure, increasing the resource of the mechanism. The second plus is that the prefilter (cloth stretched over the carbon filter) will not clog from the inside. The device itself is a capsule with activated carbon granules, which absorbs all odor molecules, pollen and fine dust. The grower receives clean air at the outlet. Capsules with charcoal have their own resource, after which they become clogged and the filter must be replaced.
Carbon filters vary in capacity. The larger the grow room area, the more efficient the device should be. The calculation is performed based on the power of the exhaust fan. 10-15% is added to it and a filter with an appropriate throughput is selected. This not only enhances the cleaning efficiency, b
ut also extends the life of the coal pellets.
For a small grow room, say, in a pantry, a MagicAir 250/100 m3 carbon filter will suffice. Its body is made of galvanized steel, which has a positive effect on durability. It uses high quality activated carbon granules that can completely remove unwanted odors from the air. The design also contains a replaceable pre-filter, which absorbs large particles of dust and pollen, thereby extending the working life of the cartridge.
An air duct is a pipe that connects one or another part of the ventilation system. It is inside it that air circulates. In the standard version, an air duct connects the luminaire with active cooling of the DNaT lamp, an exhaust fan and a carbon filter. The final link in the chain is the ventilation outlet through which the purified air is removed outside the growroom.
An example is the Aludec DA3 duct with a diameter of 102 cm and a length of 10 m. It is made of a flexible material with a multilayer structure consisting of aluminum foil, polyester and steel spirals. All this provides him with reliability and durability. Such an air duct can be easily connected to the oval and round sections of the ventilation system components. The most common clamps are suitable for fastening.
It allows air to circulate inside the grow room, which has a positive effect on the health and growth of cannabis. An ordinary household fan is quite suitable for the role of such a fan. You can also use a computer cooler. The main task is to provide a light breeze blowing so that the stems develop strong. In no case should it be a “hurricane”, therefore internal fans, as a rule, have low power. It all depends on the size of the bushes. For example, for seedlings it is better to install a computer cooler, but for lush “Christmas trees” – a small home fan. The main thing is that the air inside the grow room constantly circulates and blows the hemp bushes.