I started a sponsor grow and as communicated with @Auggie on running CO2 at 800 ppm from the start , has been running since 08/26/21 .
I manage two 12 light rooms.thought that 1500 ppm was necessary ? 800 ppm is great !!
About six months ago I did a test. The rooms just happened to have the SAME genetics in them. We used the same nutes, pest control methods, lights, etc. EVERYTHING was exactly the same in both rooms.
What a field day for a test, eh?
Room 1 ran at 850 ppm while lights on.
Room 2 ran at 1400 ppm while lights on.
Harvest weight on room 1 = 21,360 grams.
Harvest weight on room 2 = 22,800 grams.
Conclusion and recommendation to management: The extra cost involved with running at above 1200 ppm of CO2 is not worth the extra minimal production.
We run all our flower rooms at 800 to 900 ppm.