External CO₂ is an optional add-on for S1 brewers.
The S1 is a complete system on its own—you can brew, carbonate, cool, and serve without any CO₂ accessories.
External CO₂ is used only after fermentation, where it can improve serving stability, extend shelf life, and support bottling. It does not affect fermentation or carbonation inside the keg.
This guide explains when external CO₂ is useful, what connection options exist, and how to set them up safely.
Before You Begin: Do I Need External CO₂?
Most new S1 users do not start with external CO₂. The built-in Air Pump Mode already allows you to serve your beer normally after fermentation.
You do NOT need external CO₂ if:
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You drink the keg within 3 days
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You are new to brewing
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You do not plan to bottle or transfer your beer
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You prefer the simplest setup with zero extra equipment
External CO₂ is helpful IF you want:
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Longer storage (up to 15–30 days)
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More stable pouring with better foam control
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Less oxidation
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Controlled bottling/transfer
Bottom line:
The S1 works perfectly with or without CO₂. External CO₂ is simply an upgrade for users who want extended freshness or more advanced serving control.
1.Dispensing Modes After Fermentation
Once fermentation is complete, the S1 automatically enters the Cooling Program. During this stage, there are two dis pensing modes controlled by the switch on the back of the machine:
Air Pump Mode
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orange indicator
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CO₂ should not be connected (prevents mixing air and CO₂).
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The S1 automatically activate the air pump when keg pressure drops below 10 psi.
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Recommended drinking window: within 3 days.
CO₂ Mode
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green indicator
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Requires an external CO₂ system.
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Extends shelf life to 15–30 days and maintains better carbonation and foam stability.
2.What External CO₂ Is Used For
External CO₂ supports only post-fermentation dispensing functions:
✔ Serving (Cooling Mode)
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Stabilizes headspace pressure
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Reduces foaming and improves head retention
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Helps maintain carbonation during serving
✔ Transferring / Bottling
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Provides steady, controlled flow
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Reduces oxygen exposure
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Maintains carbonation while filling bottles
❌ Not Used For
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Fermentation
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Alcohol production
External CO₂ = serving & transferring only.
3.CO₂ Options for S1 Brewers
Option 1 — Mini Regulator + 16 g CO₂ Cartridges
A compact and simple system suitable for most S1 users.
Benefits:
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Portable and simple
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Easy cartridge replacement
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One CO₂ cartridge per keg
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Global standard.
(Note: The mini regulator does not allow PSI control.)
Option 2 — Single-Head CO₂ Adapter + Gas Cylinder
Ideal for users who already own CO₂ cylinders or need extended serving capacity.
Benefits:
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Suitable for long serving sessions
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Provides consistent pressure control
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Compatible with universal soda-maker cylinders (SodaStream Blue Screw-In type)
For Kickstarter backers: A discontinued 3-way adapter was included in early batches. Legacy instructions are available here: (insert link)
4.How to Connect, Set Up, and Disconnect CO₂ on the S1
These steps apply to both supported CO₂ setups.
To connet
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Prepare the gas tubeUse a clean, straight-cut tube (ID 4 mm × OD 6 mm).
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Insert the tube into the S1 gas inletPush the tube firmly into the quick-connect port on the back of the S1.
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Connect the other end to your CO₂ source
Open CO₂ slowly
Open the gas source gradually to avoid sudden pressure spikes.
To disconnect
Press the collar on the connector while gently pulling the tube out.
5.Best Practices
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Increase pressure gradually
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Store cylinders upright
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Do not use external CO₂ during fermentation
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Ensure all tubes are fully seated
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Replace CO₂ cartridges before they are fully depleted
6.Common Misconceptions
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“I need CO₂ to start using the S1.” The S1 is fully functional on its own and does not require CO₂.
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“CO₂ controls carbonation.” Carbonation occurs naturally during fermentation, not through external CO₂.
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“I need CO₂ for every pour.” Only if you want to keep the beer fresh for longer than three days.
Need Help?
If you need assistance or wish to purchase CO₂ accessories, please contact support@igulu.com.
