Pollen Glass Type-2Itsdiffusion diskis placed at a higher position than the original model. But, this doesn’t make any difference in their basic performance, such as CO2diffusing ability. Please choose as your preference.*Generally use 30mm. for 90 cm standard aquarium (approx 50 US Gallon), 40mm. for 120 cm standard aquarium and 50mm. for larger aquariums.

• Suitable for 45cm to 60cm aquarium (10~20 Gallon)