CO2 diffuser is a part of your CO2 regulation system. The CO2 regulation system usually consists of a CO2 regulator, CO2 cylinder (the source of CO2), and the CO2 diffuser. The diffuser is an add-on or standalone device and its main purpose is to dissolve the CO2 from the regulator into the aquarium.
The CO2 diffuser is attached to the tubing connected at the bubble counter as part of the CO2 regulator. The CO2 diffuser breaks down the big bubbles from the bubble counter into tiny bubbles to be dissolved into the fish tank more easily and efficiently, raising the level of CO2 in the aquarium water. It is similar to a air diffuser except it diffuses CO2 into the water. A very common one for small tanks is the ceramic glass CO2 diffuser that is submerged into the fish tank and secured to the aquarium glass with a suction cap.
Basically, the best type of CO2 diffuser is the one that makes micro bubbles, doesn’t leak,and is safe and secure. TOP AQUA New 2-in-1 CO2 Diffuser comes with high quality ceramic disc to get the optimum diffusion effect while having a integrated bubble counter to keep check. For best results it is recommended to position the diffuser just above the substrate and beneath the outflow from your filter. This gives the CO2 bubbles maximum time as they rise to the surface, and are then dispersed around the aquarium as they enter the water flow from the filter, further extending the time the CO2 is in the water and can be diffused.