I am using a small air pump in my fermenter as well. I am fermenting sugar washes and the high sugar content reduces the oxygen capacity of the wash, aeration is an easy solution and the solution that large scale commercial operations producing high percentage ethanol for fuel use.
I also find it handy as I have a third tube coming from my fermenter dropping down to the middle of my wash and if I unplug it and pinch off my CO2 tube it builds pressure and forces wash out the third tube without opening and exposing my wash to potential contaminants in the air. This allows me an easy handy and sanitary way to test Ph as sugar wash has tendency to drop down to as low as 3.5 Ph after 2 to 4 days of fermenting.
If you use an air pump to aerate I suggest building a small sealed box with a HEPA filter to filter out any fungal or mold spores and any bacteria out of the air that you are pumping into your fermenting chamber.