[avianlyric]

Plants produce CO2 as well, photosynthesis is only used to produce sugars, normal respiration (I.e. sugars + O2 = energy + CO2), is used by plants to consume those sugars.

Only a plant cells containing chlorophyll and exposed to sunlight will photosynthesise. Notably at night there isn’t much sunlight, so normal respiration dominates a plants gas conversion processes, and results in them producing net CO2.

Based on the graphs in the blog post, I assume GP is placing the CO2 production on plants because it the CO2 levels peak at night, then return to normal every morning.

[mschuster91]

Yep, I've noticed this as well with my cannabis grow tent. At an 18/6 lighting schedule, it's noticeable that CO2 grows up to 800ppm in the tent at the end of the fake-night cycle.