CO₂ Valved Cylinder for Aquariums - 3.5kg

If you’re running a planted aquarium, a steady and reliable supply of CO₂ makes all the difference. This 3.5kg CO₂ cylinder is a great option for hobbyists who want longer runtimes between refills and a clean, professional setup.

Built to AS/NZS 1841.6 standards, this cylinder is safe, durable, and refillable at most gas suppliers across NZ and Australia. It comes fitted with a W21.8 valve, which is the standard fitting used here — so it works with all compatible regulators on the market.

Why this cylinder?

• Perfect size – 3.5kg gives you months of CO₂ for medium to large tanks.
• Certified safe – Meets NZ & AU requirements for refillable cylinders.
• Standard fitting – W21.8 valve works with all local regulators.
• Built to last – Powder-coated steel body with a solid brass valve.
• Refillable – No waste, just take it in for a refill when empty.

Specifications

• Capacity: 3.5kg CO₂
• Height: 57cm (with valve)
• Diameter: 15cm
• Valve: W21.8 (NZ/AU standard)
• Standard: AS/NZS 1841.6 certified

Good to know

• Always keep the cylinder upright and secure.
• Check for leaks when setting up your regulator.
• Refills are available at most authorised gas suppliers.