CO2 Strategy: When It Pays, and How to Deliver It
The light-temp-CO2 triangle, the ~1,200 ppm sweet spot, lights-on-only injection, sealed-vs-vented logic, and why enrichment is wasted below ~800–900 PPFD.
CO2 is a light multiplier, not a standalone lever
Cannabis is a C3 plant: at ambient ~400 ppm, CO2 supply limits the carbon-fixing enzyme and a meaningful share of captured light energy is burned off in photorespiration. Enrich the air and you relieve that limit — but only if light and temperature are already high enough to use the extra carbon. This is the rule that governs the whole CO2 decision: enrichment amplifies light; it does not replace it. Below roughly 800–900 PPFD the plant is light-limited, not carbon-limited, and every dollar of CO2 is wasted. Above that, and with temperature raised to match, enrichment to ~1,000–1,500 ppm lifts photosynthetic rate on the order of 40–50% and delivers reported dry-bud gains in the ~20–43% range.
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