I've tried a lot of co2 diffusers over the years. Always in the search of the perfect diffuser. Most use a white disc that clogs up quickly to algae. These with the brown diffuser don't grow algae nearly as much. On top of that they are made out of acrylic plastic instead of glass. So they won't break in your hands when you try and install them.
- Mini is meant for nano tanks up to 10 gallons.
- Medium is meant for 10 to 30 gallon aquariums
- Large is meant for 40 gallons and up.