1. What a CO2 cylinder adapter does
An adapter sits between a small CO2 cylinder and an aquarium CO2 regulator; makers build them for small threaded cylinders. The adapter screws onto the cylinder, the regulator onto the adapter, and the CO2 then runs through tubing to the diffuser. This lets you use an aquarium regulator without a large cylinder.
According to the manufacturer, the CO2Art Pro-Series CO2 Adapter lets a CO2Art regulator run from a small CO2 bottle. The Strideways adapter is made for a regulator with a W21.8 thread. In both cases the cylinder, adapter and regulator form one chain, and every joint in it must be tight.
2. Choose the adapter by thread
First check which thread your regulator has. CO2Art makes the Pro-Series adapter in several versions: with a CGA320 or W21.8×14 thread on the regulator side, and separate versions for small CO2 cylinders and disposable M10x1 bottles. The adapter we carry has the W21.8×14 thread on the regulator side.
The elbow shape lets the regulator sit horizontally, and the adjustable on/off pin valve opens and closes the CO2 flow. The body is a single piece, so according to the manufacturer there is no room for leaks at the thread. According to Strideways, the adapter connects a regulator with a W21.8 thread, such as the Strideways PRO CO2 Regulator, to a standard Sodastream cylinder.
Quick Connect cylinders, with a pink clip and no thread, do not fit these adapters. The adapters are made for threaded cylinders, so check the neck of your cylinder before choosing.
3. A regulator with the W21.8×14 thread
The adapter needs a regulator with a W21.8×14 thread. The CO2Art Pro-Elite Series V2 and the Pro-SE Series are both dual-stage regulators with a built-in 12 V DC solenoid valve. The W21.8×14 thread (BS341 / DIN477) is the European standard for CO2 cylinders.
According to the manufacturer, the Pro-Elite Series V2 suits aquariums of 5–5000 litres, and its working pressure is adjustable up to 5 bar. Two gauges show the cylinder contents and the working pressure, the needle valve sets the flow, and the manifold block can supply several aquariums or diffusers.
The Pro-SE Series working pressure is adjustable up to about 40 PSI, roughly 3 bar, and the regulator has a bubble counter with a built-in check valve. According to the manufacturer, the dual-stage design stops the output pressure from rising as the cylinder pressure drops, so there is no sudden burst of CO2 at the end. The solenoid's power adapter runs on 100–240 V.
4. Installation and safety as the makers describe it
Following the CO2Art Pro-Elite Series V2 instructions, place the washer between the cylinder and the regulator, tighten the regulator with a spanner, open the cylinder valve and set the working pressure with the front knob. With a small cylinder the adapter sits in between, so check that the seal is in place at the joint between adapter and cylinder. As the manufacturer advises, check the connections for leaks after every installation.
Set the working pressure for whatever the CO2 goes to. For the Pro-SE Series and Pro-Elite Series V2, CO2Art suggests 10–20 PSI for reactors, 20–30 PSI for ceramic diffusers and 30–40 PSI for high-pressure diffusers. The bubble rate depends on your plants and tank, so follow the manufacturer's instructions.
Tropica advises turning the regulator fully off before changing a cylinder and protecting your hands with a towel or oven glove when mounting the regulator, because the gas is under pressure. The Tropica CO2 System Nano Cylinder 95 g is the replacement cartridge for the Tropica CO2 System Nano, not a Sodastream cylinder.
5. Seals, maintenance and cylinder exchange
The seal sits at the joint between the adapter and the CO2 cylinder and keeps that joint leak-free. The CO2Art Seal Replacement is a pack of three seals that, according to the manufacturer, fits both the Advance and Standard versions of the CO2Art Pro-Series adapter. Keep spare seals at hand so you can replace a worn one straight away.
For replacing the o-rings in the on/off pin there is the CO2Art Pro-Series Adapter Repair Kit. It includes a sealing washer, a hex key, two rubber o-rings and a black hex nut.
Sodastream runs its own cylinder exchange; we do not refill cylinders. How long one cylinder lasts depends on the setting, the tank and the plants.
Parts for connecting a small CO2 cylinder
| Product | Connection | Note |
|---|---|---|
| CO2Art Pro-Series CO2 Adapter | W21.8×14 on the regulator side | Elbow adapter, on/off pin |
| Strideways Sodastream Adapter | W21.8 regulator (maker's data) | Quick Connect does not fit |
| CO2Art Pro-Elite Series V2 | W21.8×14 | Up to 5 bar, 12 V solenoid |
| CO2Art Pro-SE Series | W21.8×14 | About 40 PSI, bubble counter |
| Tropica CO2 System Nano Cylinder | Tropica CO2 System Nano | 95 g, disposable |
Checklist
- Check the regulator thread: W21.8×14 or W21.8.
- Check that the cylinder is threaded; Quick Connect does not fit.
- Choose the adapter by the regulator thread.
- Put the seal and washer in place.
- Open the cylinder valve and set the pressure as the maker suggests.
- Check the connections for leaks after every installation.
- Keep spare seals and the repair kit at hand.
Products for this guide
Fits: CO2Art Sodastream adapter, CO2Art Pro-Series adapter for small CO2 bottles
€8.99
Frequently asked questions
Which adapters are made for a Sodastream cylinder?
By the makers' data: the CO2Art Pro-Series adapter for small CO2 bottles and the Strideways adapter for regulators with a W21.8 thread. Quick Connect cylinders do not fit these adapters.
What CO2 hose or tubing do I need?
Use CO2-resistant tubing. Check the regulator and diffuser instructions for the connection size.
How long does one cylinder last?
It depends on the setting, the tank and the plants.
Can the cylinders be refilled?
Sodastream runs its own cylinder exchange. We do not refill cylinders.
