Discover the importance of grow tent ventilation

A proper grow tents ventilation is one of the important factors if you want to pursue healthy and productive indoor growing. Thinking about home cultivation without the help of a correct ventilation system would certainly be unrealistic and unsuccessful.

As is well known among growers, temperature and humidity play a fundamental role in the healthy and lush growth of plants. Only thanks to a ventilation system for grow tents, appropriately calculated on the volume of the environment, is it possible to recreate these conditions.

The purpose of this guide is to try to understand together the importance of air recycle in grow tents and which extractors fan are suitable for having an efficient ventilation system.

Grow tent ventilation tips

Forced ventilation for air exchange in grow tents occurs by means of extractors or fans specially mounted at the entrance and exit of the cabinets

This is a very sensitive topic that encompasses various realities,
such as domestic or industrial use, ventilation of blind bathrooms (without openings), kitchens or healthcare environments. In general, in every working environment with adequate ventilation, it breaks down multiple pathogens, eliminates odors, helps create healthier environments

Nonetheless this is certainly applied to our home crops. As mentioned in the first paragraph, temperature and humidity strongly influence the lush growth of your plants.

Furthermore, plants, unlike humans, need large doses of CO2 to carry out photosynthesis, first of all cannabis. Temperature, humidity and C02 levels vary with air exchange. These parameters can be managed and maintained only by means of appropriate extractors or fans which ensure both a correct exchange of air in the grow tents  and the replenishment of the necessary CO2 .

Below we analyze point by point the fundamental importance of correct air exchange in grow rooms.

• Constant air exchange helps to replenish the appropriate levels of CO2 necessary for the chlorophyll photosynthesis process. This parameter can only be managed by correct air recirculation. The most experienced growers add carbon dioxide to the grow rooms with special CO2 systems which gradually deliver carbon dioxide, significantly maximizing the harvest. Having reduced quantities of CO2 means slowing down the development of the plant and decreasing the quantity of the harvest .
• Another fundamental aspect of good air exchange is lowering and maintaining a stable temperature, particularly when using HPS or MH lamps. Generally when we talk about Cannabis, the average temperatures during the hours of light accepted by the plant range from 21°C to 30°C, a tolerance that is lowered to a minimum of 18°C ​​and 18°C ​​in the flowering period. Maintaining optimal temperatures is also influenced by a good ventilation system.
• Another point on why it is important to equip the grow room with a ventilation system is the maintenance of relative humidity. High humidity can be reduced by increasing the power of the extractor or improving the ventilation in the internal grow tents, vice versa to increase the humidity the output flow rate of the air extractor is reduced or in critical cases of low humidity we can equip our growing kit with a humidifier. Ensuring stable humidity values, avoiding excesses, also means reducing the proliferation of parasites and diseases such as mites and harmful moulds. These parameters can only be kept under control with correct air exchange and avoiding dangerous stagnation.
• As we were saying, ventilation in grow tents is also very important with the aid of clamp fans or with adjustable base. The ventilation inside the Grow Room promotes robust growth of the plants, the fans in fact producing a movement of the stems which perform a real gymnastics on the plants which strengthens the branches and trunk, as well as keeping the plants healthy.

Grow room ventilation set up

Let's now see what the main components of a ventilation system in grow tents are and how to install them for correct air recirculation in our indoor cultivation. The aspirator or extractor, which is the main instrument of the ventilation system, is also essential for correct humidity regulation, the more air you suck in, the lower the humidity level will be and vice versa.

To help us regulate the temperature and humidity parameters, some extractors are equipped with potentiometers which in some models are integrated into the extractor.

We know in detail the various components that form a complete ventilation system in grow tents and how to install the necessary equipment:

• Grow tent air injection. As mentioned in the Grow Rooms it is necessary to introduce clean air from the outside to guarantee a correct exchange of air, this task is carried out by axial aspirators or medium or small sized fans, in larger environments the role of air injector can be covered by classic helical or centrifugal air extractors.
  The introduction of air must necessarily take place from the lower part of the cultivation environment, therefore our injector must be installed in the lower part of the grow tent. It can be placed inside or outside the tent based on the space available, in correspondence with the special nozzle supplied. The collection of incoming air must always take place from the outside, if possible, with flexible ducts.
  In both amateur and professional cultivation it is good practice to install a dust filter, preferably with activated carbon, an excellent barrier against insects and weeds.
• Air Extraction. Air extractors are the tools necessary to carry out this function. There are various models with various powers always chosen according to the Volume of the Grow Room, based on which a certain number of Air Changes will have to be carried out which will guarantee correct replenishment of the CO2 and optimal temperature and humidity levels. Unlike the injection, the air extraction takes place in the upper part of the grow tent, also in this case the grow tents on the market are equipped with vents in the upper part. The outgoing air must always go outside, never into the same environment where the grow tent is located, in this regard we always suggest placing the tents adjacent to openings or windows.
  It is of fundamental importance that the flow rate of the Extractor must be greater than the Air Injector, we will explain why in the following paragraphs
• Activated Carbon Filters . Another necessary tool in home cultivation is an adequate filtering system for eliminating odors, a task performed by an Activated Carbon Filter. Particularly when it comes to Cannabis, its use is essential. It can be installed directly with the appropriate flanges on the extractor, always in the upper part and inside the grow tent. If the extractor is located outside the tent we can always connect the distance with a segment of flexible aluminum pipe, a distance which in general is always better if it is less than 2 m. In addition to the VKO 100mm - VK01 125mm lines which do not support such filters, most extractors on the market are designed for Activated Carbon Filters without compromising their correct functioning.
• Internal ventilation grow tent . As mentioned previously, Indoor Ventilation, i.e. the movement of air within the cultivation space, is also fundamental for the healthy and luxuriant growth of the plant. It can be carried out with classic fans and special fans mounted along the structure of the grow tent, always based on the space we have available.
• Flexible Ducts and Fittings. Flexible pipes, generally made of aluminium, will be used to connect the Extractor Aspirators to the various openings both in the Grow Room and to the external openings for the collection of clean air and for the exit of the air from the cultivation environment.
• Meters and Potentiometers. there are tools such as potentiometers, thermo-hygrometers or timers that do not directly influence the functioning of our ventilation system, they are essential for keeping various parameters under control, some of these accessories help us understand if our system is functioning correctly. For example, the thermohygrometer is essential for measuring humidity and temperature levels, parameters kept stable only by correct air recycling.
• Control units for temperature and humidity:
  finally, depending on the budget you have available, the use of special control units for temperature and humidity control is strongly recommended.
  These control units, by means of appropriate and precise sensors, regulate the temperature and humidity to our liking, regulating the flow of air in introduction and extraction. This expedient always allows constant values ​​in the grow rooms with consequent benefits for your crops.

Grow tent ventilation guide: ensure healthier cultivation

Having air stagnation in your home crops would be equivalent to having a fertile field for numerous pathologies such as parasitic insects or, even worse, mold which would compromise your harvest. For this reason we will never tire of saying that ventilation and air exchange in grow rooms are essential.

For example, in the full flowering phase, most cannabis varieties grown indoors fear the onset of mold, the dreaded Botrytis. They form or proliferate as a consequence of air stagnation.

The only functional remedy is prevention, that is, constantly keeping the humidity and temperature parameters under control and with the aid of an adequate ventilation system for the recycle of air in the grow room.

For example, a good filtering system also placed at the air inlet in indoor cultivation limits the intrusion of spores or insect eggs.
An example could be the common plant mites, they appear in our indoor crops towards the warmer months. Their proliferation in the Grow Rooms is due to an environment that is too humid and hot, therefore with incorrect management of the grow tent ventilation system. If prevention is always better than cure, let's ensure an excellent ventilation and ventilation system for your grow room.

Grow tent ventilation diagram: how to calculate the air volume

There are various schools of thought and there is very often debate about the formula relating to the calculation of the volume of air exchange in grow tents necessary in home cultivation, to ensure that CO2 is replenished, in order to speed up the growth of plants.
Since there are many plants suitable for indoor cultivation and the needs of the plants change at various stages, these values ​​may differ as the cultivation cycle progresses.

However, from our direct experience and quoting agronomy books, the average air exchange in m3/h necessary for a constant replenishment of CO2 inside our grow room seems to be:

[GROWBOX VOLUME in m3] x [ ​​1/ 1.5] x [60 Minutes]

• Our formula consists of a first variable data which corresponds to the volume (V) of the grow tent expressed in m3.
• The second parameter is a constant that goes from 1 time in the vegetative phase up to 1.5, some say 2 times the cubic volume per minute from which we can obtain an average value that corresponds to 1.75. This calculation helps us to know the minimum or maximum flow rate that our air extractor must have.
• The third and final data is also a constant and corresponds to a period of time, [60 min] or one hour, it helps us complete the calculation thus knowing the hourly flow rate of the extractor. Our final value will be expressed in m3/h.

Let's take a practical example; We have just purchased a 2m3 grow tent, equivalent to a 100x100x200 cm model or 2m3. We therefore want to know the average air exchange that we must guarantee and which extractor fan is right for us, always for the right ventilation in the Grow Room .

2m3 [V] X 1, 50 [average constant] X 60 [min] = 180-200 m3/h

Thanks to this simple formula we know that our 2m3 grow tent will have to fit an air extractor which has an average flow rate of 200 m3/h.

Grow tent ventilation system and negative pressure

Which extractor can I install for efficient grow tent ventilation?

The first thing to take into consideration is certainly the maintenance of negative pressure. But what is negative pressure and how is it obtained in a grow tent ventilation system?
If you have ever seen an efficient grow tent turned on, you will have noticed that the canvas walls tend to compress inwards. This compression or "vacuum effect" typical of traveling by plane is called negative pressure. But how is it obtained and what is it for?

Very simply, negative pressure is obtained by extracting a greater volume of air than is introduced. In fact, all you need to do is mount an extractor that is more powerful than the one that introduces the air and you're done.

The greater extraction power compared to the introduction will cause this vacuum type effect, called negative pressure. But be careful, there are very precise parameters to create an adequate negative pressure in a ventilation system for grow tents.

In this regard, it is necessary to install an extractor that produces an air volume approximately 25% greater than the inserter.
Example: With a 240 m3/h extractor, an air introducer of approximately 180/190 m3/h will be needed.

Below we have reported standard volumes referring to some types of grow tents on the market and larger cultivation spaces. The table will help us choose which air extractor to install depending on the m3 we have available.

ATTENTION:

• These data take into account the normal average reduction in the flow rate of the extractors caused by the application of activated carbon filters and flexible ducts (up to a maximum of 2 m)

• It is not possible to use activated carbon filters with the VKO 100 and VK01 125 axial air extractor models

Grow tent air recirculation which extractor to choose?

To understand which air extractor to choose for your indoor cultivation, the first thing to make sure is that the extractor is proportionate, in terms of power, to the grow tent chosen. in any case, as mentioned in the previous paragraph, the fundamental rule to follow in every cultivation is that the volume of air extracted must be greater (about 25%) than the incoming volume .
We list the main extractors and in which cultivation environments they are most suitable: