Pond Boss Forums AERATION Systems questions DIY Aerator

Vertex and all disk membrane brands that I know have built in check valves. I've looked with magnification at both disk brands and several others. Flexair and Vertex have the same size pores ~1mm. Each Vertex diffuser has a special built-in air disperser valve that evens out the air flow among multiple diffusers, however this feature causes a slight increase of air pressure needed to operate / inflate the diffuser. This causes the pump to operate at a slightly higher psi which has been discussed previously on this PB Forum. I do not know how much of an advantage it is to have this special internal valve. FlexAir diffuser appears to visually operate very adequately compared Vertex diffuser. The difference is IMO likely not significant, although I have never seen any brand comparison of disk diffuser brands for air - water flows.