I have had the airline problem as well. Sometimes it plugs with salt
buildup or whatnot, I just clean it out and it works fine. I found if you
have a powerhead on the water intake it works wayyyyy nicer too. (if you
don't already have one)
I'm not sure what you mean. I'm using the pump it came with. Are you
suggesting directing the output of an additional powerhead to the intake of
the pump that came with the unit, or replacing it?
TomW