[syncopadence]

I've heard two different things: the first being right before pitching the yeast (complete joy of homebrewing) and the second source says right after pitching (this website). So which is it? I'm inclined to believe right before pitching because you don't want to mess with the yeast once it starts doing its thing. Anyway any help is appreciated. Thanks.

[mainebrewer]

I aerate before pitching, but I doubt if it makes any difference.

[HoosierBrew]

I aerate before pitching - don't know how likely it is that it stresses the yeast to aerate after, but it's extra insurance not to risk it on a regular basis.  Though, a few times I've spaced and forgotten to aerate first and never suffered anything catastrophic aerating after pitching.

[klickitat jim]

Chill, then oxygenate, then pitch for me

[pete b]

I oxygenate just before pitching then give a pretty thorough stir after pitching so the slurry doesn't just sink to the bottom. I'm not sure the post pitch stir helps but I doubt it hurts.

[Frankenbrew]

I oxygenate just before pitching then give a pretty thorough stir after pitching so the slurry doesn't just sink to the bottom. I'm not sure the post pitch stir helps but I doubt it hurts.

+1 I do the same thing, exactly.

[kramerog]

I do whenever it is convenient.  If my dry yeast is hydrated before I've aerated, I'll pitch first.  For "big" beers, I'll aerate again the next day.  I also aerate when racking to the fermenter, add yeast and then aerate gain by swirling the fermenter

[jtoots]

I used to aerate after pitching, but after participating in a similar thread now aerate towards the tail end of chilling, pre-pitch. 

[erockrph]

I aerate whenever I remember to do it. I usually shoot for pre-pitch, but it's usually the one thing I forget at the end of a long day. It's usually right as I'm pouring in my pitch when I get that sudden "dammit" moment when I realize I didn't aerate. At that point I'll just aerate after pitching.

[pete b]

The good thing about oxygenating just before pitching every time is that it has become such a habit that I never forget because I have done it so many times that pitching yeast = aerating first.

[denny]

I've heard two different things: the first being right before pitching the yeast (complete joy of homebrewing) and the second source says right after pitching (this website). So which is it? I'm inclined to believe right before pitching because you don't want to mess with the yeast once it starts doing its thing. Anyway any help is appreciated. Thanks.

It makes absolutely no difference between those 2 choices.

[jeffy]

I've heard two different things: the first being right before pitching the yeast (complete joy of homebrewing) and the second source says right after pitching (this website). So which is it? I'm inclined to believe right before pitching because you don't want to mess with the yeast once it starts doing its thing. Anyway any help is appreciated. Thanks.

It makes absolutely no difference between those 2 choices.

I don't know how much difference it makes, but pure oxygen may not be good for yeast.  You want to aerate the wort as opposed to aerating the yeast. 
I use O2 and pitch afterwards, but I've also aerated a second time several hours later for very strong beers.

[brewinhard]

I have always aerated after pitching to allow the yeast to absorb as much O2 in solution as possible.  Never had any issue with this method. 

[curtism1234]

My friend taught me to aerate after pitching and also to rock/shake the fermentor every few days. I brew 2.5gal batches so it's easier for me to do that.

[majorvices]

I've heard two different things: the first being right before pitching the yeast (complete joy of homebrewing) and the second source says right after pitching (this website). So which is it? I'm inclined to believe right before pitching because you don't want to mess with the yeast once it starts doing its thing. Anyway any help is appreciated. Thanks.

It makes absolutely no difference between those 2 choices.

I don't know how much difference it makes, but pure oxygen may not be good for yeast.  You want to aerate the wort as opposed to aerating the yeast. 
I use O2 and pitch afterwards, but I've also aerated a second time several hours later for very strong beers.

Yeah, this is what I have always heard as well. Let the pure o2 dissolve into solution before pitching yeast. I actually killed a yeast starter with pure o2 once.