CO2 Enrichment for Increased Yields

Indoor cannabis cultivators will do everything in their power to enhance photosynthesis. From high-powered lighting apparatuses to complete high-end nutrients, growers spend vast sums of money to ensure their plants are getting everything they need. One of the most important factors in the chemical equation that makes up the photosynthetic process is carbon dioxide. Because of this fact, many indoor horticulturists take advantage by supplementing additional CO₂ to the CO₂ that is already present in the atmosphere. The first thing any grower who wishes to use CO₂ must do is to decide which CO₂ method to use. 

Mycelium-based CO₂ Devices

Mycelium-based CO₂ devices are the CO₂ buckets or bags sold at hydroponic stores. These CO₂ devices use a medium to cultivate mycelium (fungus) which produces CO₂ as a byproduct as it grows. The bag or bucket is placed in the grow area and the CO₂ produced by the mycelium mixes with the atmosphere and raises the CO₂ level. These devices work great for small areas like closets or grow tents. They do not produce any heat and do not require automation equipment to operate. The disadvantages are that there is no control over the amount of CO₂ in the room and they are not really practical for large grow operations. 

Compressed CO₂ in Tanks

One way growers can boost the CO₂ in the grow room is by using compressed CO₂ in large tanks or canisters. These tanks require a regulator to release the CO₂ into the atmosphere. A timer, the CO₂ tank, and the regulator are all that are required to start supplementing CO₂ but the entire system will work more efficiently with the addition of a CO₂ controller. A CO₂ controller will monitor and regulate the actual CO₂ levels in the garden. These levels are determined and set by the user. The fact that they do not create any heat and have the ability to be fully automated is why so many growers opt for CO₂ enrichment with the compressed tank method. The disadvantages of this method are the handling and transport (the tanks are heavy and bulky). 

CO₂ Burners

The most popular choice for CO₂ enrichment in large areas is CO₂ burners. These devices burn either natural gas or liquid propane and emit CO₂ in the process. CO₂ burners come in various sizes, including very large units designed for large greenhouses or commercial buildings. Like compressed tanks, CO₂ burners are most efficient when automated by a CO₂ controller. The controller determines when additional CO₂ in the grow area is needed and ensures a consistent level of CO₂. The advantages of CO₂ burners are they are suited for large areas and they are relatively cost efficient. The disadvantage of CO₂ burners is the heat they emit can build up in the grow area if not properly addressed. 

The CO₂ Concentration 

Once the gardener decides what device to use for CO₂ enrichment, they need to decide on the concentration of CO₂ they wish the grow room to have. Considering the ambient CO₂ concentration in our air is just under 400 PPM (a bit higher in more populated areas) any CO₂ enhancement beyond that level will give the garden some benefit. For beginners I normally recommend starting at 700-900 PPM. This is because the higher the CO₂ concentration in the room, the higher the operating temperature must be to effectively use the CO₂. At 700-900 PPM of CO₂, a grower can operate the room at 75-80 degrees F and still get the full benefits from the CO₂ they added to the atmosphere. More experienced growers, or growers confident in their control over the room’s environment,  the CO₂ levels can be pushed to 1500-1700 PPM. In order to gain the full benefit from this high concentration of CO₂, the room’s operating temperature needs to be around 82-87 degrees F. Along with increasing temperatures, growers will need to adjust the nutrient concentration accordingly. Plants stimulated by increased CO₂ will require a higher concentration of nutrients. 

Along with high-powered lighting and quality nutrition, CO₂ enrichment is an essential component to maximizing production in an indoor garden. By utilizing one of the devices to enrich the environment’s CO₂ concentration, cannabis cultivators can manipulate the photosynthetic process and reap the rewards in prolific harvests.  

Eric Hopper is the Editor in Chief for NUGL Media. He can be contacted at [email protected].