Bright Green new growth? Is Co2 to blame?

Looks like iron defiency . I use Magne Cal + up to 0.4 ec before adding anything else . The + is trace elements like iron,boron,zinc

I have no experience in c02 being added to the grow, I know its not need unless you have all the other environmentals in check like light DLI and temps and RH or VPD and then feeding. Its used to increase the DLI past 40 with out damage and allow higher temps in the grow space. If this is your first grow with it, save yourself some money and don't use CO2 till later in your growing adventures. The room also needs to be sealed or its just going to vent out. and If your venting into your living space vs outside extra CO2 is not ideal, its all ready higher in homes vs outdoors. Other then that, the colourization also resembles low iron and sulphur content in the medium. FYI: We will not be notified of any reply or tag [@] in the questions part of the website, if you need to reach out with other information use your DM "direct mailbox" in the bottom right hand corner of the page. it looks like a little paper airplane icon. Good Luck!

Yea it can be that also remember when ur in and out of the tent the co2 will rise and maybe slightly high but should be fine might be the plant adjusting.