Cannabis grow ventilation system ideas

One way to ensure circulation of fresh air that is supplied by the extraction system is through use of fans. The fans help distribute CO2, humidity and temperature throughout the tent or growing area. Without such ventilation, it is highly probable to get smaller yields and you still risk destroying the crop due to excess humidity or heat. There are distinct types of fans that can match any situation as illustrated:

Oscillating fan this should help circulate air to neutralize hot spots and to create a cool breeze that facilitates transpiration. You will need at least 1 medium sized fan regardless of the size of the room, but for bigger rooms use one oscillating fan for every three 1000 watt lights. You should feel air movement in the growth space and the crops should slightly move alongside the air. 

Carbon filter you can attach a carbon filter to facilitate the exhaust fan in removing the odors accumulated in the tent or room.

Exhaust fan get a fan with excellent cubic feet exhausted per minute rating that should help replace air in the growing tent or entire room at least every 1-3 minutes.

To choose a reliable fan it is advisable to calculate the cubic area of your space that is length multiplied by width and by height. Also take into account the efficiency of the fan; for instance if the exhaust travels a straight but short path, double the area (multiply by 2). And if the path is twisted or quite long, multiply the cubic area by 3. Then select a fan that has a CFM higher than the number you have calculated especially if you will fit a filter in it.

To facilitate air intake, you should create ventilation for the fresh air to enter the room or tent. Just make a simple hole that is 3-4 times bigger than the exhaust hole; otherwise, you would need to include an intake fan to complement the exhaust fan.

Extraction system

An extraction system that is fitted with carbon filter is also required since cannabis plants just like any other plant need carbon dioxide to grow. The carbon filter is simply a large tube that is full of carbon; which helps absorb chemicals such as gases and odors produced by plants.

The filter is critical since if you do not provide fresh air, the plants might use all the CO2 in the growing area and instead slow down growth. The extraction system helps suck the CO2-depleted air to the outside and bring fresh CO2-rich air. The system also helps do away with typical odors that the plants release during the flowering stage.

Setting meters

It is mandatory to set up meters such as pH meter, humidity meter, a thermometer, timers and other accessories to determine the best growth conditions. The best environmental conditions for growing your marijuana plants should be as follows:

1. Temperature Range

For the lights-on cycle, the crop requires temperate conditions that range from 70-80 degrees F; while for lights-off cycle, a range of 64-71 degrees F. If growing the crop without CO2 augmentation, a temperature setting of 73 degree F is advised for day cycle growing. But with CO2 augmentation, the crop requires higher temperatures of 76 degrees F. If growing marijuana in pots whether in cement slabs or basements, you should not put the pot directly on the floor as this might cool the root zone. Try to maintain a root zone temperature of around 67 degrees F for better productivity.

2. Grow Room Humidity

Ensure to maintain 40% to 65% humidity throughout the vegetative phase and 40 to 60% in the flowering phase. Do not allow excess humidity as this can create mould and trigger infestation of other harmful organisms.

3. Light Cycles

Set your timer to 18 hours light cycle and 6 hours off during the vegetative growth phase. For the floral flowering phase, set it to 12 hours light on and 12 hours lights off.

4. Light Measuring

As light is measured in lumens, you should get a lumens meter that can properly respond to light just like camera light meters do. Ensure that the top of the plant canopy receives about 3000 lumens of light to support the vegetative and flowering

phases. To find out if your plants are getting inadequate light, both visual inspection and a light meter should apply. Areas such as corners or the bottom of the canopies are more likely to be light deficient so check them out. Ensure continuously that your plants get the required amount of light to prevent growth patterns which translate to lower yields.

5. Light Coverage

For stationary light, a 400 watt bulb should provide light for up to 10 square feet of space. A 1000 watt light bulb should offer enough light for around 20 square feet of space. To extend the coverage area, consider using light movers.

Atmospheric Requirements

Crops need sufficient oxygen at the root zones and higher amounts of CO2 on the underside of the leaves. Ensure that the total room carbon dioxide is around 1500 parts per million, which translates to about 400 PPM natural levels of CO2. For this reason, it is recommended to do CO2 augmentation to boost CO2 levels especially in cases where the temperature settings are above average. To do so, install a CO2 emitter and time it in relation to exhaust fan to ensure that CO2 is not expelled from the room.

Supply enough water

The rule of the thumb is to provide water that has a pH value between 5.7 and 7.0, preferably without dissolved minerals. If you use tap water, ensure it is not too acidic by adding premixed solutions such as wood-ash or lime available in garden centers. If the water is too alkaline, add phosphoric acid, sulphur or a premade pH lowering solution. In case you live in areas where tap water has many minerals or is too hard, you may want to filter the water preferably using reverse osmosis filtration technique before use. However, this method is quite expensive and it yields water of lower quality compared to spring or well water.

Triggering the Flowering Cycle

After the plants have developed enough and get to flowering phase, it is time to supply enough light beyond the default 12 hours of light in a day. Thus you will need to include lamps with the strongest source of light as the crop is in its photoperiod of flowering. As it is impossible to get 12 hours of daylight, consider moving the crops into an enclosed location like a cabinet or closet and then hang lamps overhead. Then you will need to control light cycles through a timer that is set to a 12 hour period.