Inline diffuser size

[Jconner3]

I'm Getting ready to order an atomic inline co2 diffuser and I don't know which size to get. The 12/16mm or the 16/22mm? My filter is the fluval 306 and I also bought the rubber adapters so I don't have to replace the tubing.

 

[Richardwm]

You will need the 16/22 mm due you your hose being 3/4 in or 17 mm