We have looked at some commercially available solutions complete with grow tent ventilation kits to see what extractor fans the manufacturer has chosen.
The grow room fan schedule can be the same as your light cycle because ventilating a grow room is really necessary only during the day.
CFM Grow Tent Calculator
In this case, no carbon filter is necessary for the cool tube circuit: the fresh air will be taken directly from outside the tent and pulled through the cool tube to the other side, never mixing with the air inside the tent.
Cannabis Ventilation At Night
A passive ventilation system makes use of the fact that the hot air always rises. So you only need one vent in the bottom part of your grow space and another — in the upper part. When the air gets heated by the lights, it goes out the tent through the upper hole. This creates the negative pressure, and the cool air from outside enters the tent through the bottom hole.
Adjusting the temperature and humidity parameters
Ona Duct is used to eliminate odours
This is why, normally, air extraction fans are used in all indoor grow rooms, to which growers connect carbon filters to remove the odour from the plants while also removing heat and humidity. For improved performance, growers also use intractor fans (always of lesser airflow capacity than the extractor fans, so negative pressure is created and odours don’t escape the growing space through holes or zippers) which are constantly supplying the grow room with fresh air from the outside. Finally, using fans inside the growing space is also recommendable, since they produce a constant airflow that helps avoiding heat/air pockets.
Climate control systems for cannabis grow rooms
If we want to be more accurate, there are several climate control units on the market that will help us to have the perfect environment for our plants. We just have to connect our extractor/intractor fans to these units and set the desired temperature/humidity range. The unit will control our ventilation system by turning the connected devices on/off when necessary. Our grow room should be at 26-28ºC with the lights on and at 20ºC with the lights off.
Rotating clip fan
Properly ventilated grow room
Ventilation and temperature in indoor grow rooms
A commonly used formula to know the necessary airflow capacity (m3/h) of our extractor fan is top calculate the total volume of our grow room (m3) and remember that our extractor should renovate all the air of our room in less than 5 minutes. Of course, and in regard with temperature, it is not the same using CFL’s or LED panels than HPS lamps. The temperature of our grow room also depends on both the airlfow capacity of our intractor fan and the place where the air comes from: it is quite different having the air intake inside the house than in a shady and fresh corner of our backyard. Thus, before purchasing our extractor fan, we must take into account both the total volume of our grow room and the lighting system used.
Air intractor fan