EHEIM CO2 pressure regulator for aquariums, disposable or refillable cylinder
Regular price
$77.80
Regular price
Sale price
$77.80
Unit price
/
per
$25.93 × 3 with no fees
Klarna.
The EHEIM CO2 pressure regulator reduces the cylinder pressure of around 60 bar to a stable low working pressure, and finely adjusts the bubble rate thanks to its precision valve.
Available in a version for 500 g disposable cylinders, or a 2-gauge version for refillable cylinders.
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The summary
- Which version: depending on the thread of your cylinder.
- What it does: reduces roughly 60 bar to a stable low pressure, with precise dosing.
- The gauges: on the refillable version, to keep track of the remaining gas.
- The adjustment: bubble by bubble, using the bubble counter.
From the cylinder to the bubble counter, a stable pressure and precise dosing
The EHEIM CO2 regulator reduces the pressure of a cylinder, around 60 bar, to a stable low working pressure, in the region of 1.5 bar, and sets the flow bubble by bubble thanks to its precision metering valve. It comes in two versions depending on the thread: M10 × 1 for disposable 500 g cylinders, and W 21.8 × 1/14" with 2 pressure gauges for refillable ones.
A CO2 cylinder contains liquefied gas under a pressure of about 60 bar at room temperature, far too high for aquarium pipe. The regulator screws onto the cylinder and brings this pressure down to a low, stable working pressure of around 1.5 bar, which the rest of the installation can withstand. Its precision metering valve then sets the flow, bubble by bubble, which you watch on the bubble counter. It is the central component of any pressurised CO2 installation, and the regularity of the supply to your plants depends on it.
🔩 Two versions, two thread sizes
CO2 cylinders do not all have the same thread, and it is the thread that decides which regulator you need. The version for disposable cylinders screws onto an M10 × 1 fitting, the one found on 500 g disposable cylinders; it has an adjustment knob and a precision dosing valve, without a pressure gauge. The version for refillable cylinders screws onto a W 21.8 × 1/14" fitting, the one found on cylinders that you have refilled, of 500 g or 2 kg. It also has 2 pressure gauges: one shows the cylinder pressure, the other the system pressure.
Disposable 500 g bottle
The M10 × 1 version, without a pressure gauge.
Reusable bottle
The W 21.8 version, with 2 pressure gauges.
Large planted tank
The reusable one, cheaper in the long run.
Small tub
The disposable: simple and compact.
A bottle stored upright, wedged in place and kept cool
CO2 is odourless and heavier than air, and it causes asphyxiation at high concentrations. Use the cylinder upright, secured so that it cannot fall over, in a well-ventilated room, never in a basement, away from sunlight and from any temperature above 50 °C. Never force open a cylinder.
⚖️ Disposable or reusable
The two versions are not interchangeable: a regulator for a disposable cylinder cannot be screwed onto a refillable cylinder, and vice versa. If you switch from a disposable cylinder to a refillable one, which is more economical for a large tank, you will therefore need to change the regulator as well, while the rest of the installation can be kept. Refillable cylinders may only be refilled at an approved CO2 refilling station, and disposable cylinders must never be refilled: once empty, they go off for steel recycling. If you are starting from scratch, the EHEIM pressurised CO2 kit includes the cylinder, pressure regulator, diffuser and pipe.
A CO2 test to adjust according to a measurement
The number of bubbles does not tell you what level the water reaches, because that also depends on circulation and on how much the plants consume. The dissolved CO2 drop test gives you that level, so you can adjust the dosing valve on a measurement rather than by guesswork. You avoid both too little, which holds plants back, and too much, which distresses the fish.
🔧 Installing the pressure regulator
Before connecting the regulator, turn the adjustment knob fully towards the minus sign and close the fine-dosing valve. Check that the seal on the threaded fitting and the sealing surface of the cylinder valve are clean and undamaged, then screw on the regulator and tighten it by hand, without tools: on a disposable cylinder, a brief hiss may occur. Next, cut the CO2 pipe to the required length, slide on the locking nut, push the pipe all the way onto the regulator fitting and tighten the nut. The regulator can be removed at any time by following the steps in reverse order, with the cylinder closed.
💨 Adjusting the flow rate
On the reusable version, first open the main valve on the cylinder, then turn the adjustment knob until the system's pressure gauge shows the pressure your setup needs. On the disposable version, it is the adjustment knob that opens the CO2 supply. Then open the fine-dosing valve until you see bubbles reaching the diffuser, starting with a small amount, then increase it over several hours until you reach the desired level. Take a planted 100-litre aquarium: with an EHEIM diffuser, the starting point is about 10 bubbles per minute, a value you then fine-tune.
The working pressure varies slightly with room temperature, which is why it is worth checking the flow rate every week. With the dual-gauge version, the cylinder needle stays steady almost to the end, because the CO2 is liquid in the cylinder, and then drops quickly: that is your signal to have it refilled. With a disposable cylinder, you know the gas is running out when the bubbles slow down. Check the fittings for leaks with soapy water every time you change the cylinder, never use a damaged CO2 pipe, and keep the regulator indoors, in a room where the water stays between 4 and 35 °C.
🌱 In aquaponics
Pressurised CO2 remains rare in aquaponics, where the fish and bacteria already produce it. It finds its place in a heavily planted aquaponics aquarium, where you grow demanding aquatic plants under strong lighting, whereas the vegetables in the grow beds draw their carbon from the air and do not need it. A precise regulator then prevents overdosing, which would lower the pH to the detriment of the fish, whereas the target range in aquaponics remains 6.4 to 7.5. The article on regulating pH in an aquaponics system explains how to monitor this value.
Technical specifications
Disposable bottle
- Fitting
- M10 × 1
- Bottles
- Disposable, 500 g
- Pressure gauge
- None
- Adjustment
- Adjustment knob and precision dosing valve
Reusable bottle
- Fitting
- W 21.8 × 1/14"
- Bottles
- Reusable, in 500 g and 2 kg sizes
- Pressure gauges
- Bottle and system pressure
- Warranty
- 2 years
In the box
- 1 CO2 pressure regulator with precision metering valve, depending on the version chosen
Fittings, instructions and safety information from the manufacturer EHEIM (manual 6063040 and 6063050), recorded on 13/10/2026.
Manufacturer and product safety
- Manufacturer
- EHEIM GmbH & Co. KG
- Postal address
- Plochinger Str. 54, 73779 Deizisau, Allemagne
- Contact
- info@eheim.com
- Website
- eheim.com
Information provided under Regulation (EU) 2023/988 on general product safety.
Which regulator for your cylinder?
Two thread types, two regulators. The cylinder decides.
Disposable or reusable?
One answer, and the table highlights the right regulator.
| Thread | Bottles | Pressure gauges | Price | |
|---|---|---|---|---|
| Recommended disposable or refillable cylinderYour choice | M10 × 1 | Disposable 500 g packs | None | $77.80 |
| disposable or refillable cylinderYour choice | W 21.8 × 1/14" | Reusable, 500 g and 2 kg | Two | $143.11 |
disposable or refillable cylinderRecommended
Compatibility
ThreadM10 × 1
BottlesDisposable 500 g packs
Pressure gaugesNone
disposable or refillable cylinder
Compatibility
ThreadW 21.8 × 1/14"
BottlesReusable, 500 g and 2 kg
Pressure gaugesTwo
Low working pressure, around 1.5 bar, in both cases.
Help choosing
One question is enough
Documents & manuals
Official EHEIM instruction manual
Instructions for both regulators, multilingual including French: CO2 safety, assembly and commissioning.
Document not showing? Some publishers block display inside a frame, so open it in a tab.
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Frequently asked questions
10 questions
6 key questions, 10 in the detailed view
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