I’m intending to try co2 enrichment with Exhale bags.

And from reading on the co2 enrichment I understood that photosynthesis does not play a role during night time and the plant actually emits co2.

  1. I wonder if the bag should be sealed during “lights off” period? So the plant won’t be flooded with co2
  2. I also read that the co2 level should be around 1200-1500 ppm, but the light intensity is also an important parameter and it should be measured as well. So I will need to buy a co2 meter and a light/lux meter. The prices for those two are ranging from relative budget pricing to very expensive:

Are those measuring tools should be sufficient for my purpose ?

  1. What is the lux level for effective photosynthesis to occur when co2 enrichment is involved?

Growing setup:

  1. Plant: let’s keep it private - one plant in 90x90x160 tent.
  2. Light: x4 COB CREE CXB3590 - 200W in total.
  3. Growing medium - Coco perlite mixture.

If any other information is missing please write it and I’ll add.

  • The links don't work.
    – alephzero
    Feb 2, 2019 at 17:26
  • I don't think you should spend money on extra CO2, there is plenty in the environment already. The benefit of extra CO2 is minimal to none.
    – benn
    Feb 3, 2019 at 8:37
  • Many people report on the benefits of adding co2... I also used co2 in form of dissolve tablets in my previous growing session and in the vegetative period the results were absolutely different. So I’m not intending to invest thousands of dollars on such system, but I’d like the idea of exhale’s bags...
    – Wuid24
    Feb 3, 2019 at 16:50

3 Answers 3


I will answer as much of your question as I can, but I am afraid that I cannot answer it fully. Normally plants don't need extra CO2. There is plenty of it in the air already. But if you want to add some extra for whatever reason, here is what you should know:

  • Lux is not the unit you should be looking for. The numbers you want are provided in PAR.
  • Feeding extra CO2 is useless unless you are above 1000 PAR at least. I don't know the grow lights you specified, but an intake of 200W on a growing area of 0.89m² doesn't sound like you are getting anywhere close.

So I would recommend to save the money for the exhale bags and the CO2meter and spend it on something more useful.

If you want to know more about the topic, search "How big a grow light do I need?" by the channel "migro" on Youtube. You might find a lot of interesting information on that channel. (Sorry I can't provide the link, I am at work and can't access YouTube)

  • Thanks for the elaboration on the PAR parameter. Those devices are very expensive from the first search I saw...
    – Wuid24
    Feb 4, 2019 at 18:19
  • @Wuid24 Yes, they are really expensive. But you don't always need one for yourself. The channel I told you about does a lot of lamp testing and also measures the PAR values. A good producer will also give a PAR distribution of his product. Feb 14, 2019 at 7:27

Some years ago I saw data on growing young pine trees , I think a university in N or S Carolina. At about 900 ppm ( double the atmospheric CO2 at the time) they saw significant improvement over the control group; so you do not need the levels you mentioned. The tests were outside so normal light. The CO2 level was more or less constant . They described high plastic sheet walls with an open top and a steady input of CO2.


If you had biology at school, you have probably heard that photosynthesis is divided in a light-dependent reaction and a light-independent (or "dark") reaction. During the dark reaction CO2 plays a role, so short answer to your question is not to close bags during night time.

However, as an extra note I would like to add (see my previous comment) that it is very unlikely that these CO2 bags in your home-grow setting will benefit your crop. It is indeed possible in a large well controlled greenhouse to gain extra harvest by adding CO2 (with optimal light, temperature, and nutrient conditions, etc.). However, for your home-grow setting there are too many uncontrolled factors, and because it is on such a small scale, that adding CO2 will not be beneficial. But don't let me discourage you, if you think it will work, give it a try. Good luck.

  • In fact, i did a co2 experiment back in my school days, that is why the subject came up to me. I took 2 mints and put them in two separate small green house that I’ve built. One with co2 that I’ve produced with candles :) and the other without the results were significantly better from the mint in the co2 greenhouse. Currently I’ve managed to control the environmental and nutrition parameters, steady temp, humidity, enough light...
    – Wuid24
    Feb 4, 2019 at 18:10
  • But in the ‘dark’ reaction the plants are emit co2 ? So excess co2 won’t affect the process ?
    – Wuid24
    Feb 4, 2019 at 18:18
  • Did you put out the candles at night? Excess CO2 is what you want, right?
    – benn
    Feb 4, 2019 at 20:29

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