I have a pretty solid foundation of plant basics and growing. I was recently reviewing the MMAR application for designated growers in Ontario and one of the questions asked: If CO2 is being used, during what weeks of the growing cycle is it not necessary or in fact, detrimental to crop health? What is the maximum CO2 ppm you should ever have in your room? I was of the impression that co2 is beneficial at all stages of growth. Of course as long as lighting, nutrients etc. are all increased to supply the plants growth. If anyone could shed some light on this for me that would be greatly appreciated. Thank you very much in advance and I hope to hear from you soon.