[majorvices]

I've been doing a lot of flavor threshold experiments switching between using pure o2 and compressed air. Pretty sure I get better results, faster, stronger ferments that reach better attenuation faster with pure o2 for lagers. Ales may tend to lose a little bit of esters from the pure o2 but again, I see stronger, faster fermentation and better attenuation with pure o2 on ales as well. Still not sure which I like for ales yet but I know that I'm leaning toward pure o2. Yeast flavors may be cleaner but I think I like the results better.

I definitely agree with a second addition of compressed air after 12 hours for beer over 1.080. I see a much shorter fermentation time with crisper flavors with the second addition.

As always YMMV.

That's interesting to hear.  I haven't done any side by side ferments, so it's hard to see the impact.

Not side by side, just from about 6 weeks of tracking data. Certainly nothing firm.

[majorvices]

IMO if you are repitching yeast or making big beers you definitely want to make sure they have sufficient o2 whether from o2 tank, shaking, etc.  If you are making normal strength beers (1.056ish) and not reptiching  dont worry about it much

I've been stir starting from smack packs then repitching out to 4 or 5 generations, before starting all over.

I don't think this is going to make a huge difference, but I'm kind of getting down to just small differences left to make. I'm kind of running out of process improvements to make.

I think  your going in the right order. I think you'll notice some deduction in lag, some speed up in fermentation and perhaps some better attenuation.

[klickitat jim]

Cool, a small improvement with greater consistency would be great

[Joe Sr.]

That's interesting to hear.  I haven't done any side by side ferments, so it's hard to see the impact.

Not side by side, just from about 6 weeks of tracking data. Certainly nothing firm.
[/quote]

If you're tracking data, it's far better than trusting my memory.  If there's an impact from pure O2 (and I like to believe there is) then I think it is subtle enough to require someone tracking data like your doing or else going side by side.  Me looking back at my less than stellar notes isn't going to cut it.

[euge]

Notes?

[Steve L]

Sorry for 'partially' hijacking the thread but I myself brew 2.5 gallon batches and oxygenate with pure O2. For a typical 1.050 ale I use 45 seconds at 1LPM. Could I be over-oxygenating? There's precious little info on the interwebs about 1/2 batches and oxygenation. My attenuation and lag times seem OK but some of the milder ales I've brewed seem a bit lackluster in flavor and have a noticeable, albeit very light sherry/cardboard flavor. I oxygenate after the wort is chilled into the 60's so I don't think it's HSA. Can over-oxygenation cause these flavor issues? I may need to cut back to a 1.2 LPM... Thoughts are greatly appreciated

[klickitat jim]

It sounds like oxidation. From what I have gathered, so long as your fermentation is proper, HSA oxidation should be cleaned up. (Unless you are doing something crazy I suppose)  So I would be more inclined to think it's a packaging or storage issue. Over oxygenation usually results in hot solventy fusel alcohols. Lack luster makes me think that you may be oxygenating to a point where the yeast are fermenting a little too clean for your taste. You might try cutting the exposure time down to 30 seconds.

Disclosure: These thoughts are all based on study. My O2 regulator and stone just showed up today...

[Steve L]

It sounds like oxidation. From what I have gathered, so long as your fermentation is proper, HSA oxidation should be cleaned up. (Unless you are doing something crazy I suppose)  So I would be more inclined to think it's a packaging or storage issue. Over oxygenation usually results in hot solventy fusel alcohols. Lack luster makes me think that you may be oxygenating to a point where the yeast are fermenting a little too clean for your taste. You might try cutting the exposure time down to 30 seconds.

Disclosure: These thoughts are all based on study. My O2 regulator and stone just showed up today...

that reinforces my thoughts too. I've only done about 6 batches using O2 and the beers with the ones with more specialty grains or those mashed at higher temps have more character. I think I'm gonna try either 30 seconds @ 1LPm or stick with 45 seconds @ 1/2 LPM.

I think you'll like the O2. My rotator cuff and tendinitis have vastly improved since I stopped shaking!

[hopfenundmalz]

The recommendations I have seen is 1 liter/min for a minute in 5 gallons of regular strength beer. I use that for my lagers. For 2.5 gallons cut the time, or the flow, in half.

I was using O2 for everything, and found my British ales that should have ester character to be too clean. Now those just get air from pumping over to the fermenter, no shaking or mix stir.
Edit - if racking from the kettle to the fermenter, then I would use the mix stir or shake.