I purchased the Sera large,Max mix large and UP inline diffuser with a porous core . I have a fluval 406 the UP seemed the most logical small convenient no moving parts. I noticed that it can dissolve up to 1000 CO2
microbubbles in a minute, which is plenty for a 100-gallon tank. On the other hand, if you have a small aquarium or do not have that many plants, you can dial the pressure down.