Aerating with Oxygen

pilotdane · 07-28-2009, 12:29 AM

Any idea how much oxygen (flow rate, time) is a good starting point when using a .5 micron stone in a 5 gallon batch?

Droot · 07-28-2009, 12:32 AM

I don't remember the size of the stone, but the instructions said 50 seconds.

David

**Bobby_M** · 07-28-2009, 12:34 AM

Pretty much as slow as you can get it to flow for 60 seconds. You want the wort to absorb it, not create a crap load of foam on the top.

SourHopHead · 07-28-2009, 12:34 AM

Oxygenate is a better word to use.

I use 1-2min for a 5gal batch. Sometimes less cuz Star San foams like mad.

pilotdane · 07-28-2009, 11:46 AM

Thanks. I have been doing way too much than. I have been doing 10 minutes at 2 liters/minute and getting quite a head of foam on top. I was not concerned when I used an aquarium stone but with the more efficient .5 micron stone I started to wonder if I could over do it and kill the yeast with too much O2. Good news is 1 minute will use a lot less O2.

Thanks

**Bobby_M** · 07-28-2009, 01:59 PM

Since you brought up exacting flow rates (I assume you have a medical reg), I run .25 l/m for 60 seconds.

pilotdane · 07-28-2009, 05:21 PM

You are correct it is a medical regulator. I like knowing "how much" O2 is flowing.

I have been reading articles online for several days and one will contradict the other. Here is an interesting one: MB Raines, Ph.D. - Guide to Yeast Culturing for Homebrewers - Maltose Falcons Home Brewing Society (Los Angeles Homebrewing)

Here is a quote from about half way down the article discussing oxygen levels.

"In general, it is difficult for homebrewers to achieve sufficient oxygen levels. The levels of oxygen necessary for optimal fermentation vary depending on the yeast strain. Ale strains usually need between 8-12 part per million (ppm) while lager strains require slightly higher amounts (10-15 ppm). At atmospheric pressure the maximum level of dissolved oxygen in wort is approximately 8 ppm and the saturation level decreases further as the gravity of the wort increases. Thus unless special steps are taken to introduce air or oxygen into the wort, it is difficult for homebrewers to achieve adequate aeration. Recent studies have shown that oxygenation is by far more efficient than aeration. Injection of oxygen through a 2 micron diffusing stone can actually supersaturate the wort with 10-12 ppm of dissolved oxygen being reached in 5 gallons of wort by a single 60 second blast of oxygen!"