RDWC, Mephisto,Forum Stomper, Co2, Scrog

High, it looks to me like your plant is suffering from an Iron deficiency. This can not be caused by such a low Co2 value. The plants love a value between 1200 to 2000 ppm. This small amount is not dangerous for humans. The outside air contains around 500 ppm and from 3000 ppm it start to be dangerous and harmful for humans. It is always good to give them some extra Co2 and it really works when you've got a high quality lamp from 400 watts per m² like you do! I would give them around 1200 ppm during the whole grow. And to fix you iron deficiency, here is a link with an article about everything you need to know about how to solve and fix it: https://www.growweedeasy.com/cannabis-plant-problems/iron-deficiency Happy and healthy 2023