Boiling off oxygen in extract or partial-mash brewing is a bit of a non-issue when only doing a partial-boil. The top off water should have plenty of oxygen still in solution. Aerating the wort becomes more imperative when doing a full boil. In my case that is when I brew three gallon batches at home, or when Andy and I brew five to ten gallon batches.
The air we breath is mostly hydrogen and only around 21% oxygen. You can introduce some oxygen to your wort by agitating your fermenter, splashing the wort when you transfer it to your fermenter, running your wort thru a strainer, or otherwise agitating it.
For awhile I used pure oxygen. I purchased an oxygen regulator, oxygen tank, and diffusion stone to oxygenate my beers.
This setup worked decently enough. Having to go to a big box home improvement store to buy the oxygen tank was a minor inconvenience. Unfortunately by the time my tank was empty the regulator had rusted onto the empty tank. When this happened I decided to try the aquarium pump.
No tanks are needed, just plug the little guy in and let him pump away! The air filter makes sure contaminants in the air aren't pumped and diffused into your beer. As long as I take reasonable care of the thing this is a one-time purchase other than replacing the filter one a year or so.
The main advantage to the tank is that it is pure oxygen. The tank with regulator does not take as much time to diffuse the wort as the pump. With the tank I would let it rip for anywhere from 30 seconds to two minutes. The instructions that came with the pump suggested leaving it in for 30 to 120 minutes.
I used the pump for the first time the other day. I didn't mind the time it took. Once I cooled down my wort and transferred it to the fermenter, I plugged in the pump and let it do it's job while I finished cleaning.
A propperly aerated wort will start fermenting more quickly than a wort that isn't. My first batch was going within 12 hours. That's even more impressive since I was using dry yeast. So far, the pump feels like a solid investment.
See Oxygen - How to Brew
Follow me on Twitter @JChalifour
Like The Would-be Brewmaster on Facebook
Share what beers you are drinking with me on Untappd