Carbon Dioxide setups – Suggestions on Improving Set up

Author: Scott  


Hi, I was wondering if you could help me out .

I currently grow in a room which is 10.5ft (3.3m) x 8ft (2.7m) with 2x1000W and 1x600W during grow and introduce 3x400W in flowering. I grow 3 plants at a time. My question is would my room benefit from the introduction of Co2 and would my room be too big to use the Electro Co2 Unit. Your assistance would be much appreciated. SB

Hello, I can help you with the Hydroponics.

CO2 should make your plants grow at a faster fate, but usually don’t finish sooner. Their metabolic age is greater but held back by their physical age.

For CO2 to help, you need to have temperature under control 20-30 degrees always, and very little ventilation required. Air conditioning is a must I believe to ensure this happens despite the ventilation being turned off.


CO2 regulator, flow meter with 240V solenoid sold at BOC gases as a greenhouse kit.

CO2 gas bottle. You hire this from BOC gases. Make sure you have the right thread (left or right handed thread)

Exhaust fan and inlet fan for room

Circulation fan


Calculate CO2 required

1500ppm gives enhanced growth. 2000 will slow plants, and below 1000 no improvement. normal air is 300ppm so 1500 less 300 in air is 1200 to enrich the room. 1200ppm is 1200 parts of co2 in 1million parts of air. So work out how many litres of air are in the room. 1mx1mx1m is 1 cubic meter = 1000litres of air 10cmx10cmx10cm = 1litre to work out the litres required to achieve 1200ppm you divide the number of litres in the room by a million and multiply by 1200 (or just multiply the litres in the room by 0.0012) The 1mx1mx1m area is 1000litres and needs 1.2litres of CO2 to enrich it. So just put the regulator and flow meter set at .6litres per minute for 2 minutes, or .3litres per minute for 4 minutes or 1.2 litres per minute for 1 minute by using a digital timer.

You need to follow the 4 stages of CO2 injection.

1. Exhaust the room and bring in fresh air. Since normal air is 300ppm approx, this will give you a starting level of CO2 in the room and make sure the room is below 30 degrees for the whole period. I suggest around 10 air changes to remove any old co2 down to 300ppm normal outdoor levels. check fan cubic meters per hour to work how long to run them to get 10 air changes.

2. wait for fans to stop (60 secs.)

3. Inject CO2 from a gas bottle with a regulator and flow meter set to inject the right amount of CO2 to reach 1500ppm.

4. wait until either CO2 has leaked out, been used, might be gone but you don’t know, (around 30mins to 3 hours) and go back to step one.


If temperatures rise above 30 degrees the plants are stressing from heat and may become more heavily stressed faster because of the higher metabolic rate of the plant. Plants can die in an afternoon if the room is bad enough, where without CO2 they would have only become sick and been able to recover.

Infra red CO2 detection and injection

Infrared detectors can add CO2 as the levels drop. Can be an expensive system so I’ve never used one, but told it is great but not worth the money.

Hope that helps


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