O2 to Imperial Stouts

Conventional wisdom is to add O2 to at least 12 ppm with a gravity this high. Then hit it again with the same amount, 12 - 18 hours after pitching to support the first cell division. I have never made a beer as large as you plan, but would tend to error on the high side.

 

If you have an O2 system that'd be at least a minute at the time of pitch and at least another minute the next morning. Vikeman has a formula for O2 addition lengths, I believe.

 

I brewed a 1.120 RIS a couple months ago.

Hit it with 1.5 minutes of pure O2 right before I pitched. Then I hit it again the next morning, so roughly 10-12 hours, for another minute roughly.

After that.. stay out of it.

 

One needs to state what batch size. 5 or 10 or 1 barrel. Just saying...

 

I usually add direct o2 to every beer under say 1.050 OG on its way from the chiller to the fermenter with my inline oxygenator. About 3 weeks ago I brewed the biggest beer I've ever made. It was a RIS with a starting OG of 1.116 and while I did use my oxygenator, I (2-3 days) later noticed the pores on the stainless steel airstone were very clogged and only a fraction of the usual amount of oxygen I add made it into the wort. I was also worried because the carboy didn't show much krausen at all. I was really worried that I had a stalled fermentation so I took a gravity reading. Much to my surprise the beer was already down to 1.035 SG, still fermenting away gently (goal of 1.027 FG) and reached it's terminal gravity about a week after that. Fermented it with a mixture of 2 parts WLP007 and 1 part US05 to a glorious 12% abv.

 

Sorry I meant to say I usually add direct o2 to every beer OVER say 1.050 OG and I wanted to add clarity to something I was trying to suggest in my previous post. While adding oxygen is very important, yeast strain choice and pitching rate still factor into the equation. Some yeast strains prefer more oxygen while others do well with lower amounts. Some pitch rates require less yeast growth during the initial phase of fermentation to accomplish a healthy fermentation. Some dry yeasts have agents in them that reduce the need for more sterol growth I believe.

I under oxygenated my latest RIS by my usual standards, didn't add a second blast 1-2 days into fermentation, it was the highest OG beer I've brewed to date, and it still hit the targeted 75% attenuation in a timely 10 days because I had the right yeast for the situation. Heck I probably would have got more than 75% attenuation but the 12% alcohol environment tends to be the ceiling for the strains I used this time.

Makes me wonder if I've been babying my yeast too much prior to this brew. I've talked to more than one incredible brewer who has suggested that its best to try to dial your ferments right into the fine line between a stressed and an adequate pitching condition to produce amazing products. Like a fine wine that comes from some terribly rocky soil / stressed grapes, sometimes adversity produces true hero's!

 

For 5 gallons, use around 1 to 1.5 minutes at 1 liter/min flow before you pitch. Hit it again around 12 hours +/- after pitch with the same amount. Do not add O2 once the yeast are fully active. Do not add O2 when moving to secondary, actually you want to minimize any O2 introduction after the yeast are fully fermenting.

 

Sure you can do it, but it is not best practice, and can lead to oxidation after the yeast has finished the primary fermentation.

Which forum(s)?

 

Once the yeast have finished propagating, more oxygen doesn't help with fermentation. At that point, you want them making beer, not more yeast (which they probably won't do anyway under the conditions).

 

I believe C02 is most likely what they might have used in those situations.

 

Yes. I have blown yeast off the bottom of my conical with CO2.

 

For a big beer more O2 is better. With an aquarium pump you will get a lot of foam before optimum levels are reached, so you might have to hit several times in the first hour or two. Use a sterile inline filter if you go this route.

 

With an aquarium pump you will be limited to 8 ppm, regardless of how long you blow bubbles. To get above this level you must use pure O2:
http://www.wyeastlab.com/hb_oxygenation.cfm

From Yeast:
Pure oxygen injected at 1L/min through a 0.5 micron stone into 20L of wort at 75F gives these results:
60 sec - 9.2ppm
120 sec - 14.1ppm

For the best results on a beer this big, you really should beg, borrow, or steal an oxygen tank.

 

They might have used Co2, but I've never done it.