Air Pump Needed?

[thejon]

Greetings all!  
 
I'm working on setting up my 72g again, and am wondering if I need to bother with buying an air pump.  I'm running a FilStar XP M, so I'm turning over my water 4ish times per hour, but I'm not breaking the water surface at all. I worry that, even though I have lots of 'swirls' at the top of my tank, I'm not getting good gas exchange.  
 
Do I need an air pump to break the water surface some? If so, what's the purpose of "bigger' air pumps.  Is it just overcoming the water pressure at the bottom of the tank?  If so, could I (for my purposes) attach a smaller pump to a bubble wand, and just stick it about 1 inch below the water line? 
 
Thanks all!

 

[techen]

Can you not put the filter up so it breaks the surface? You need it for good oxygen exchange. A airpump would easily do this though, yes.

 

[thejon]

Actually, I just did exactly that.  I thought I lost my elbow piece for the return, but I found it.  Makes quite a difference. Thanks!