CO2 Schlauch PRO 4/6 mm (2 m)

CO2 Schlauch PRO 4/6 mm (2 m) — Gas-Tight Tubing for Pressurized CO2 Systems

If you've invested in a pressurized CO2 setup, the tubing connecting it all together matters more than most hobbyists realize. The CO2 Schlauch PRO 4/6 mm is a purpose-built silicone hose that carries CO2 from your regulator to your diffuser without the slow, invisible gas loss that standard airline tubing allows. At 2 meters long with the industry-standard 4 mm inner / 6 mm outer diameter, it's built to be the reliable "last mile" of any planted tank CO2 system.

What Makes It Different

Ordinary silicone or vinyl airline tubing — the kind sold for air pumps — is not designed to hold CO2. Over weeks and months, CO2 molecules slowly permeate through the walls of standard tubing, which means your bubble counter can be lying to you: you're injecting X bubbles per second, but less CO2 is actually reaching your plants than you think. This tubing uses a food-safe silicone formulated to resist that gas permeation, so the CO2 you dose is the CO2 your plants actually get. It also stays flexible in cold conditions rather than stiffening up like PVC-based hoses often do, which makes routing it around tight cabinet corners far less frustrating.

Key Benefits

• CO2-resistant silicone construction minimizes gas permeation loss compared to standard airline tubing
• Stays soft and flexible even in cool cabinet environments — no cracking or stiffening over time
• Smooth, coated surface resists dust and grime buildup, keeping the line looking clean
• Universal 4/6 mm sizing fits virtually every regulator, solenoid, bubble counter, check valve, and diffuser on the market
• 2-meter length is enough for most under-cabinet CO2 setups with room to route around obstacles
• Food-safe material — no leaching of harmful substances into aquarium water
• Softens slightly in hot water for an easier, tighter push-fit onto glass fittings

Technical Specifications

• Inner diameter: 4 mm
• Outer diameter: 6 mm
• Length: 2 meters
• Material: food-safe, CO2-resistant silicone
• Maximum working pressure: Manufacturer has not officially published this specification.

Who Should Use This

This tubing is for anyone running a pressurized CO2 system on a planted or aquascaped tank — from a first-time high-tech setup to an experienced aquascaper maintaining several tanks. It's also the right call if you're replacing an aging hose: silicone tubing does degrade over time, and yellowing, stiffness, or visible cracking are signs it's due for a swap. If you're only running DIY or yeast-based CO2 at very low pressure, standard airline tubing may be sufficient, but for any regulator-driven system, CO2-resistant tubing like this is worth the small extra cost.

How to Install It

Cut the tubing to the length you need with a clean, straight cut — a sharp blade prevents crimping at the cut edge. Push it firmly onto your regulator or solenoid outlet, then run it to your bubble counter, check valve, and finally your diffuser. For glass diffusers or glass lily pipes, dip the last centimeter of tubing in hot (not boiling) water for a few seconds to soften it; this lets it slide onto the glass fitting easily and then grip tightly as it cools, forming a gas-tight seal without needing a hose clamp in most cases.

Expert Tip

A hose that looks fine on the outside can still be leaking CO2 through its walls if it's the wrong material — this is one of the most common, hardest-to-diagnose reasons a planted tank's CO2 levels seem to drift even though the bubble count hasn't changed. If your drop checker is running greener than expected despite a consistent bubble rate, checking your tubing is one of the first things worth ruling out, right alongside checking for loose fittings. As a general rule, plan to replace CO2 tubing every 2–3 years, or sooner if you notice yellowing or stiffening.

Frequently Asked Questions

Can I use regular airline tubing instead of CO2-specific tubing?
You can, but you'll likely lose more CO2 through the tubing walls over time, which makes dosing less predictable and wastes gas. For a pressurized system it's not worth the small savings.

Is this tubing safe for a shrimp or fish tank?
Yes — the silicone used is food-safe and won't leach anything harmful into your water.

How do I get a tight seal on glass fittings?
Soften the end of the tubing briefly in hot water before pushing it onto the glass connector. It will shrink slightly and grip firmly as it cools.

Will 2 meters be enough for my tank?
For most under-cabinet setups where the CO2 cylinder sits next to or below the aquarium, 2 meters covers the full run from regulator to diffuser with some to spare for routing. For larger tanks or cylinders placed further away, you may want to plan the route in advance or combine two lengths.

Does this tubing work with my existing regulator and diffuser, even if they're a different brand?
Almost certainly yes — 4/6 mm is the de facto standard size across the CO2 equipment market, so this tubing fits the vast majority of regulators, solenoids, bubble counters, and diffusers regardless of brand.

Pairs Well With

• Chihiros Nano CO₂ Diffuser (M) — a compact glass diffuser that connects directly to this tubing for efficient CO2 dissolution in planted tanks.
• Chihiros CO2 Regulator Mate — an all-in-one regulator with integrated solenoid, the ideal starting point of the CO2 line this tubing completes.
• Chihiros CO2 Pressure Regulator PRO Limited Edition — a precision dual-stage regulator for hobbyists who want tighter pressure control on a high-tech setup.