Air Pump

I am coming from a FW only background...So here is my "Dumb Question" What is the advantage/disadvantage of running an air pump and air stone in my refuge to keep my chaeto ball tumbling??? Thanks for all the information Guys!!!
 
Mine doesn't turn, but my top layer is always lighter in color, but it doesn't stop it from growing, i just trim it every few weeks to keep it green.
 
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