Needle wheel impellers deal with air/water mixture better than 'paddle type impellers'. Paddle type impellers do work, but needle wheels work much better because they can handle more air in comparison.
I've ran a GenX-2400 without a needle wheel for a couple of weeks and was satisified with the results. I then threw in the needle wheel and it made an obvious difference in bubble size and density.
Not only does the impeller make a difference ... the venturis make a huge difference too. The GenX venturi sucked big time. I made my own and it made a HUGE difference in air volume.
I don't have an 'air meter' but it doesn't take a scientist or a meter to show you that the pump is drawing more air.
I wouldn't use a venturi on the output of the pump to drive a
skimmer, especially after witnessing the performance of a needle wheel type
skimmer (with or without a needle wheel impeller).
Here's my
DIY Skimmer Page:
DIY Needle Wheel Skimmer
