External CO₂ diffuser for canister filters with 12/16, 16/22 or 19/25 mm hoses. Produces ultra-fine bubbles and dissolves CO₂ efficiently before the water returns to the aquarium.
The Chihiros External CO₂ Diffuser is an inline diffuser that is installed on the hose of your canister filter. CO₂ is injected directly into the return line, so the gas has a long contact time with the water before it reaches the aquarium.
The integrated ceramic disc creates extremely fine bubbles and breaks the gas into a mist that is easily dissolved. This gives very efficient CO₂ use and helps you keep a stable level even in demanding planted tanks.
Because the diffuser sits outside the tank, there is no glassware inside the aquascape – ideal if you want a clean look without visible equipment.
The diffuser comes in three sizes that match the most common filter hoses:
M – for 12/16 mm hoses (outer Ø 16 mm)
L – for 16/22 mm hoses (outer Ø 22 mm)
XL – for 19/25 mm hoses (outer Ø 25 mm)
Choose the size that fits your hose exactly – never force a hose that is too small or too large, as this can cause leaks.
Specifications
Model
Hose size
Outer diameter
Compatible hose type
Placement
Material
Notes
Chihiros External CO₂ Diffuser M
12/16 mm
Ø 16 mm
Standard canister filter hose
Pressure side (outlet) on return hose
Acrylic body with ceramic disc
For small to medium tanks where 12/16 mm hose is used
Chihiros External CO₂ Diffuser L
16/22 mm
Ø 22 mm
Standard canister filter hose
Pressure side (outlet) on return hose
Acrylic body with ceramic disc
For medium to larger tanks with 16/22 mm hose
Chihiros External CO₂ Diffuser XL
19/25 mm
Ø 25 mm
Standard canister filter hose
Pressure side (outlet) on return hose
Acrylic body with ceramic disc
For high-flow setups with 19/25 mm hose
Recommended working pressure
CO₂ source
Installation
Cleaning
Warranty
Approx. ≥ 1.5 bar for a fine mist
Pressurised CO₂ system with regulator and needle valve
Cut the return hose and insert the diffuser in the direction of flow
Soak the ceramic disc in bleach solution and rinse thoroughly
2 years
For the best performance, mount the diffuser on the pressure side of the canister filter and avoid kinks in the hose. Always check for leaks after installation and secure the hose with clamps if needed.
