Aquarium Pump Aeration

One of the best and cheapest ways to aerate your wort for good yeast health is to use an inexpensive aquarium pump and an inline sterile air filter (not pictured).
This setup costs less than $20 at PetSmart, though your local homebrew store probably sells a full kit as well.
Yeast wants 8 to 10 parts per million of oxygen in the wort for healthy reproduction during the lag phase of fermentation.
Dr. Brad Smith in Home Brewing with BeerSmith says, "even the relatively cheap aquarium pump injection system can achieve the 8 ppm ideal aeration level needed for your wort."
He suggests running the pump for one hour after pitching your yeast.
What's needed:
Small aquarium pump, aquarium air line, inline sterile filter and an airstone to diffuse the bubbles.
Just remember to sanitize the air line and airstone!