Gonna throw a little bit on this, an increase in Co2 is only necessarily when you start reaching higher DLI levels.
When you increase the PPFD (the light that falls onto the plant canopy over a square meter) you increase the DLI, or Daily Light Integral. It’s generally accepted that a DLI of 22 is the bottom threshold for the best rate of photosynthesis without Co2, and cannabis can handle a DLI up to 65 WITH CO2.
To kinda put that into perspective, in the summertime when the sun is at its highest point, California receives a DLI of 65.
As you increase the DLI with higher end lights that give out a better PPF (light emitted from the source) your PPFD increases depending on the distance from the plant canopy. As you start to approach DLI values into the 30’s and 40’s you can start using CO2, above that CO2 is absolutely required to make use of the additional light you’re giving the plants.
Light Schedules for DLI 22:
24/0 schedule: 254.6 micromoles/m2/s-1
18/6 schedule: 339.5 micromoles/m2/s-1
12/12 schedule: 509.25 micromoles/m2/s-1
Light Schedule for DLI of 65:
24/0 schedule: 752.31 micromoles/m2/s-1
18/6 schedule: 1003.08 micromoles/m2/s-1
12/12 schedule: 1504.6 micromoles/m2/s-1
To find DLI you take the umols (micromoles) / second and multiply by 60 to get umol/minute then multiply by 60 again to get umol/hour. You then convert this into mol (moles) by dividing by 1,000,000 giving you Xmol/hour where “x” is the value after dividing by 1,000,000. You take xmol/hour and multiply it by the respective light cycle to get your DLI.
If you ever want to measure the PPFD a plant receives, you need a PAR meter, OR some light manufacturers will actually post the PPFD of their lights. (Good manufacturers usually take multiple measurements at different mounting heights) and you can use those.
In conclusion, the higher the DLI, you have the potential for a higher rate of photosynthesis (which equals more growth as photosynthesis is how plants create energy), as long as you can support the additional rate of photosynthesis with CO2, temperature and relative humidity (referred to as VPD), and with the increase in nutrient uptake, in theory your plants will yield more. Once you perfect using these different variables, the only thing that assist in your overall yield is time with traditional ways of growing. Remember, a shit grower with good genetics can only be good. A grower that has perfected the art of cultivating cannabis and has good genetics is basically Superman.