Does running CO₂ make sense for home growers?
Plants use CO₂ for photosynthesis and most home growers replenish CO₂ in the grow room with simple vents to outside.
A lot of growers consider adding CO₂ to their grow rooms to increase growth rate and yield but is it worth it?
Tests prove growth rate can increase by 30% with elevated CO₂ levels. However, it is costly and complicated system to setup and run. It is not suitable for most small home growers. It would be simpler and cheaper to add more grow space, upgrade LED grow lights or other growing methods such as upgrade to hydro.
Elevating CO₂ in the grow room requires air conditioning
Running CO₂ requires a sealed grow room so that the added CO₂ is not vented out and wasted. This means air cannot flow in or out of the grow area.
Plants produce a lot of evaporated water and grow lights and other equipment product heat.
In a closed system you must run air conditioning to remove moisture and heat from the grow room. If you are growing in a room that is air conditioned and can be air sealed you are half way there.
How to add CO₂ to the grow room with 'hot' or 'cold' CO₂ systems
To achieve 30% increases in growth rate the CO₂ level must be elevated from atmospheric 400ppm to 1,200pm. This can be achieved by 'cold' systems using a CO₂ canister, regulator valve and controller or 'hot' systems which use a gas burner.
Cost of a CO₂ control system for the grow room
For both systems you will have to purchase a CO₂ meter and controller to measure the CO₂ level and turn on and off the CO₂ supply as needed. CO₂ meters and controllers are expensive, about $600 to $1,000.
Cost of a cold CO₂ cylinder and regulator for the grow room
The CO₂ canister option is easier to add to your existing system because it does not add heat and water vapour like the gas burner. The CO₂ cylinder, regulator and control valve will cost in the region of $1,000 to $1,500 to buy. The 10 litre cylinder can be the industrial welding type and will cost about $100 to refill. A 10 litre cylinder will last about 2 months in a 5ft x 5ft grow space
Cost of a hot CO₂ burner for the grow room
The hot CO₂ burner adds heat and water vapour to the grow room which will add to the air conditioning load and cost more in electricity to run.
However a CO₂ hot burner will only cost about $300 to $600 for a home setup. They run on liquid propane gas (LPG) and are a fraction of the cost to refill.
