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Optimised lighting, calibrated nutrients, precise watering — yet your plants still plateau. The culprit is almost always the same: inside a sealed grow tent, CO2 levels drop below 400 ppm within just a few hours. At that level, photosynthesis slows to a crawl no matter how good the rest of your setup is.
The CO2BOX Boost Bag 409g solves this in the simplest way possible: one litre of water, one bag hung up, and your growing space reaches 1,200 to 1,500 ppm of CO2 for around twenty days. Zero electricity, zero pressurised cylinders, zero adjustments. It's the growth lever that many indoor growers discover far too late.
Light and fertilisers aren't enough. Carbon dioxide is the raw material your plants consume the most during photosynthesis — it alone accounts for the majority of the carbon that makes up their biomass. Tripling or quadrupling the available concentration gives your plants the means to actually use all the light energy and nutrients you're already providing.
The CO2BOX relies on a natural organic reaction activated by water. The substrate inside the bag releases CO2 gradually and consistently, with no concentration spikes or sudden drops. Unlike cylinder-based systems that require a regulator, pressure gauge and constant monitoring, there's nothing to keep an eye on here. The bag works on its own, silently, day after day.
If your lighting and nutrition are already dialled in, adding CO2 is often the missing piece that separates an average harvest from a truly impressive one. Indoor agronomy data is clear: between 1,200 and 1,500 ppm, vegetative growth becomes denser, internodes tighten and overall plant structure strengthens — exactly what's needed to set the stage for a bountiful flowering phase.
The bag contains 409 g of dry organic substrate. When one litre of tap water is added, the biological reaction starts within a few hours and produces CO2 continuously for approximately 20 days. The process is entirely self-sustaining — no timer, no sensor, no electrical connection. You activate it once and it does the rest.
Designed for spaces up to 1.44 m² (15.5 sq ft), typically a 120 × 120 cm grow tent. This is the most common format in indoor growing, compatible with Homebox tents, Secret Jardin grow tents or any enclosure of equivalent dimensions. Within this volume, the CO2 concentration remains even and stable with no risk of overdosing.
Non-pressurised system with no valves or regulators. No risk of accidental leaks, no tricky handling. You can store, move and set it up without any special precautions — a real advantage if you'd rather not have a pressurised gas cylinder inside your growing space.
Open the bag, pour in one litre of water, mix gently, then hang it above the canopy. Since CO2 is heavier than air, it naturally sinks down towards the foliage where photosynthesis takes place. This is the ideal position for efficient diffusion with no waste.
CO2 enrichment delivers the best results during the vegetative growth phase and the first two to three weeks of flowering, when plant metabolism is at its peak. For seedlings or freshly rooted cuttings, it's premature — wait until your plants are well established and growing vigorously before giving them this extra carbon boost.
Adding CO2 without adjusting the rest of the environment. For your plants to convert this extra carbon into biomass, two conditions are essential: a temperature between 25 and 30 °C (77–86 °F) and sufficiently powerful lighting. Under horticultural LEDs, you're in the perfect scenario — their low heat output gives you the thermal headroom to raise temperatures without stressing your plants.
Also think about air circulation. An oscillating fan distributes CO2 evenly throughout the space. During the light period, reduce extraction to keep the CO2 inside the tent longer. And if you want even more precise control for future cycles, an automated CO2 diffuser will let you fine-tune the concentration.
Picture this: your 120 × 120 tent is fitted with a high-performance LED, your plants are growing well but nothing spectacular. You hang the CO2BOX up high, dial back the extraction slightly. Within a few days, the difference is visible to the naked eye — denser foliage, shorter internodes, more compact and vigorous plants. They're building the solid structure that will support a flowering phase worthy of your setup.
The CO2 Boost CO2BOX Generator Bag 409g removes all the complexity usually associated with CO2 enrichment. No bulky cylinder, no technical installation, no expensive consumables — just a self-contained biological bag that works for 20 days, silently and without intervention. For anyone looking to take their grow to the next level without adding complexity, it's the most practical upgrade you can make.
Pair it with your current setup or start fresh with a complete grow tent kit for a fully integrated installation from day one. Either way, your plants finally have all the carbon they need to reach their full potential.