One of the best things you can do to promote yeast health is to provide plenty of oxygen at the start of fermentation. Oxygen is vital for yeast growth and development. But how much do you need, and how do you get there?
Professional brewers and yeast manufacturers recommend that oxygen be present in wort at a concentration of about 10 parts per million (ppm), a bit higher for lagers and high-gravity ales. The pros usually inject pure oxygen through a diffusion stone as chilled wort passes from the heat exchanger to the fermentation vessel.
As homebrewers, many of us don’t own a diffusion stone and a pure oxygen source, but you can achieve surprisingly high levels of dissolved oxygen with remarkably rudimentary techniques.