My powerhead sponge filter has a surface air tube thingy,which draws in air What is the real purpose of this?

Question

In my freshwater aquarium, There is a powerhead filter. Does it really give out oxygen to the water or just air bubbles just like an air stone would do.. Can the powerhead run without it as it is removerble and if done it seems quiet + bubble-less..

Answer 1

Its only purpose is to draw in air.  Some people still believe that the air bubbles from powerheads (and air stones) are what add dissolved oxygen to your tank.  NOT TRUE!  These bubbles are too large and rise to the surface and pop too quickly to make much of a significant impact on the amount of dissolved oxygen in the tank.  Most gas exchange takes place at the water's surface, and about all these gadgets do is to disturb the surface to circulate the water there throughout the tank (so that the dissolved O2 gets to the bottom and CO2 gets to the top).  And that happens just fine if you remove the air intake hose.

About the best use for the bubbles coming out is to get an idea of where the water stream from the powerhead is directed and how strong the flow is.