ExHale CO2 Bags Compared: Original vs 365 vs XL, and the Real Cost Per Cubic Foot
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ExHale CO2 Bags Compared: Original vs 365 vs XL, and the Real Cost Per Cubic Foot
Three sizes, one mechanism, and a price-per-cubic-foot gap that doesn't match the sticker price order. We sell all three ExHale bags. We don't upsell. Here's what each one actually covers, what it actually costs to run, and which size matches which room.
The 30-Second Answer
- All three bags work the same way: mycelium culture inside a vented bag passively releases CO2 around the clock, no electricity, no heat, roughly a 500 ppm boost near the canopy.
- The Original's own listing no longer states a coverage area or duration, and it's down to 1 unit in stock - in practice, the 365 has replaced it.
- Over the guaranteed 6-month peak window, the XL (288 cu ft) costs 29% less per cubic foot than the 365 (128 cu ft): $0.158/cu ft vs $0.221/cu ft.
- Count the 365's stated 9-month total CO2 life instead of just the 6-month guarantee, and the gap nearly disappears - the 365 edges ahead on a per-cubic-foot-per-month basis.
What an ExHale bag actually is
All three ExHale bags run on the same mechanism: a patent-pending mycelium culture lives inside a vented bag, and a microporous breather patch lets it release CO2 continuously into the air around it. There's no tank, no electricity, no heat, and nothing to refill. You hang the bag slightly above canopy height - the included freshness seal doubles as a hanger - and it does the rest.
Hydrofarm, which distributes the line, states the bags typically raise CO2 levels by roughly 500 ppm above ambient air near the bag. That's a real, measurable boost, but it's a fixed one - you can't dial it up for flower or down for veg the way you can with a tank and regulator. What you get is what the mycelium produces, continuously, for as long as the bag is active.
The three sizes: what's actually different
The 365 and the XL have specific, stated numbers on their ModernFarms listings. The Original doesn't - its current product description is generic marketing copy with no coverage area or duration attached, and it's sitting at 1 unit of inventory. For a buying decision, treat the Original as effectively discontinued in this catalog and compare the 365 against the XL.
ExHale 365 Self-Activated ($28.33) covers a 4x4 ft space - 128 cubic feet - and is rated for 6 months of guaranteed steady CO2 production. ModernFarms' own listing adds a detail worth knowing: that 6-month guarantee is the peak window inside a longer 9-month total CO2 life, on top of a 3-month shelf life before activation. Add it up and the bag is designed around a 12-month cycle - hence "365." It ships ready to use; no manual activation step, no waiting on colonization. You place it and leave it alone.
ExHale XL ($45.50) covers a 6x6 ft space - 288 cubic feet, more than double the 365's footprint - for 6 months guaranteed. ModernFarms' listing doesn't state a longer tail beyond that 6-month window the way the 365's does, so for the purposes of this comparison the XL's known, documented life is 6 months flat.
The real cost per cubic foot
Here's where the two defensible ways to do this math actually disagree.
Basis 1 - the guaranteed 6-month peak window only (apples to apples):
- 365: $28.33 ÷ 128 cu ft = $0.221 per cubic foot
- XL: $45.50 ÷ 288 cu ft = $0.158 per cubic foot
On this basis, the XL is 29% cheaper per cubic foot than the 365, despite costing 61% more upfront. Bigger bag, better unit economics - a pattern that shows up constantly in this catalog, from fabric pots to fertilizer concentrates.
Basis 2 - the full stated CO2 life of each bag:
- 365: $28.33 ÷ (128 cu ft × 9 months) = $0.0246 per cubic foot per month
- XL: $45.50 ÷ (288 cu ft × 6 months) = $0.0263 per cubic foot per month
Counted this way, the 365 is marginally cheaper - about 6.6% less per cubic-foot-month than the XL. The catch is that this credits the 365 for three additional months of lower-output production that ModernFarms' XL listing simply doesn't make a claim about one way or the other. It may run longer in practice; it isn't stated.
Sizing bags to your actual room
A single 365 (128 cu ft) fits a standard 4x4 ft tent at roughly 8 ft of height almost exactly. A single XL (288 cu ft) fits a 6x6 ft tent at the same height, or two smaller tents run off one bag if they're adjacent and share airflow - though ExHale doesn't publish guidance for splitting coverage across separate enclosures, so that's an approximation, not a spec. For anything larger than a 6x6, you're buying multiple bags: two 365s run cheaper than one XL plus a 365 if your room is closer to 256 cu ft than 288, so it's worth doing the cubic-foot math against your actual tent or room dimensions rather than defaulting to "one bag per tent."
Passive bag vs active tank and regulator: which fits your room
ExHale bags aren't the only way to add CO2, and they're not always the right one. The alternative is an active system: a CO2 tank or generator feeding a regulator, metered by a controller like the Blueprint BCC-1 Digital CO2 Controller ($71.33), which holds a room to a target between 400 and 2,000 ppm. Commercial growers chasing the commonly cited active-enrichment target of 1,200–1,500 ppm - well above what a passive bag can reach - run exactly this kind of setup.
Two things make that decision for most growers before cost does. First, an active system only pays off in a sealed room - if your exhaust fan is pulling fresh air through constantly, you're venting the CO2 out as fast as the tank adds it, whether that tank is feeding a tent or a commercial room. Second, ModernFarms doesn't currently stock the tank or regulator hardware itself, only the controller - so going active means sourcing that equipment separately and running the controller here. For a tent or a room you don't want to seal and monitor, the bags are the complete, in-stock, no-extra-hardware answer.
What We'd Tell You at the Counter
If you're running one 4x4 tent and don't want to think about it again for six months, buy the 365 - it's cheaper up front and its stated life likely outlasts the XL's in practice. If your space is a 6x6 or you're trying to minimize cost per cubic foot on a documented, guaranteed basis, the XL is the better buy per square foot of canopy. Skip the Original; its own listing doesn't give you enough to compare it against, and there's one left anyway. And if you're already running a sealed room with real CO2 ambitions above 1,000 ppm, a bag isn't the right tool at all - that's a tank and regulator conversation.
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FAQ
Do ExHale CO2 bags actually work?
Yes, within what they're designed to do. The mycelium culture inside continuously releases CO2, and the distributor states a typical boost of around 500 ppm above ambient near the bag. That's a real, passive increase - but it's fixed, not adjustable, and it works best in an enclosed space where the CO2 isn't being constantly exhausted out.
What's the actual difference between the Original, 365, and XL bags?
The 365 and XL both have documented coverage and duration on their ModernFarms listings: the 365 covers 128 cubic feet for a guaranteed 6 months (with a stated 9-month total CO2 life), and the XL covers 288 cubic feet for 6 months guaranteed. The Original's current listing doesn't state a coverage area or duration, and it's nearly out of stock.
Do I need one bag per tent, or can I split coverage?
Size the bag to your enclosure's cubic footage first. A 365 matches a 4x4 ft tent almost exactly; an XL matches a 6x6. ExHale doesn't publish official guidance on splitting one bag's output across separate, non-adjacent enclosures, so for anything larger than a single tent, plan on multiple bags sized to total volume rather than stretching one bag further than its stated coverage.
Is a CO2 bag or a tank-and-regulator system better?
They solve different problems. Bags are maintenance-free, require no electricity, and are the complete in-stock option here - but they're capped around a fixed, modest ppm boost. A tank-and-regulator setup, run through a controller like the Blueprint BCC-1, can be dialed to the 1,200–1,500 ppm range commercial growers target, but only pays off in a sealed room and requires hardware ModernFarms doesn't currently stock beyond the controller itself.
Do I need to seal my grow space for a CO2 bag to help?
It helps significantly. A sealed tent or room holds the CO2 near the canopy where the plant can use it; constant exhaust airflow vents it out as fast as the bag produces it. You don't need a fully sealed room - just avoid running intake/exhaust fans at full tilt the whole time the lights are on if you want the bag's output to actually reach the plant.
For the full picture on CO2 alongside the rest of your environmental setup, see our 4x4 grow tent setup guide.
Pricing, stock levels, and product specifications reflect ModernFarms' live catalog as of October 2026 and are subject to change. CO2 supplementation affects plant metabolism; always maintain adequate ventilation for grower safety, and never allow CO2 levels to approach unsafe concentrations for humans in occupied spaces.