Greatech Fine Bubble Membrane Diffuser Model: GD250 Diameter: 250mm Membrane Material: EPDM Dish Material: ABS Flow Rang: 0.02 - 0.13 m3/min Dissolved Oxygen Efficiency (20 degree C): 26%. Pipe Fitting ( OD 90mm ) is also available. Advantages: High Oxygen Transfer Rate Reliable Intermittent Aeration Operation Extended Lifetime Expectancy Simple Installation Procedure . Application: Biological Aeration Fishery Spots Activated Sludge Systems Wastewater Treatment Oxygenation for Sludge Digestion Ozone Diffusion in Water. By Carton.