CO2 Diffusers

A CO2 diffuser dissolves pressurized CO2 gas into fine bubbles so it can be absorbed by the water before it escapes to the surface — the key to fast, healthy plant growth in a planted tank. Which style you need depends on your tank size and how the gas needs to enter the water column.

Diffuser types in this range

In-tank glass or ceramic diffusers — sit inside the tank and release a steady stream of micro-bubbles; simplest option for nano to medium tanks.
Atomizers — produce a much finer mist than a standard diffuser, giving CO2 more contact time with the water for larger or heavily planted tanks.
External/inline reactors — plumbed into the canister filter’s outflow so CO2 dissolves before the water even reaches the tank, keeping the tank itself free of visible bubble clutter.

Pairing a diffuser with the rest of your CO2 setup
A diffuser is only one piece of the injection chain — it works alongside a CO2 cylinder for gas supply, a regulator to control output pressure, and a bubble counter to measure injection rate. See our guide to CO2 & Bubble Count for how to size a cylinder and set the right bubble rate for your tank.