When do you aerate wort?

[Craftman86]

I have a pump for fish tank that I am going to use with hose and a stone to aerate wort, but when do I do it before or after adding water?

 

[flars]

Aerate after adding the top off water. This way you will be aerating the entire wort. Splashing as much as possible while filling the fermentor will help aerate.

 

[C-Rider]

Me, Never.

 

[Kent88]

Depends.

Aerating is all about having healthy yeast. Yeast have a tough time in denser, high-gravity wort. If a beer is low gravity then I will just rely on splashing the wort around when I fill the primary fermenter, and maybe swirling it up after that. If it is a beer with moderate gravity wort I will use my aerator right around when I add yeast. If it is a high gravity beer I'll aerate when I add yeast, and then again around 12 to 18 hours.

 

[diS]

Aerate before fermentation starts, before or after adding yeast whatever you prefer.
If you top of with water, as said aerate after adding water, especially if you boiled it before since it lost some O2 with boiling.

 

[SlitheryDee]

I usually aerate immediately after pitching the yeast. I aerate by agitating the fermenter, so that gets the yeast well mixed into the wort. That probably doesn't make a significant difference, but it makes me feel satisfied, so I do it.

 

[Irishguy42]

Depends.

Aerating is all about having healthy yeast. Yeast have a tough time in denser, high-gravity wort. If a beer is low gravity then I will just rely on splashing the wort around when I fill the primary fermenter, and maybe swirling it up after that. If it is a beer with moderate gravity wort I will use my aerator right around when I add yeast. If it is a high gravity beer I'll aerate when I add yeast, and then again around 12 to 18 hours.

What thresholds do you consider to be moderate and high gravity?

 

[Kent88]

@Irishguy42 I haven't completely settled on the numbers, but in this case I'd say that I consider light gravity to be below 1.048ish, and high gravity to be above 1.075.

For me it can vary a bit depending on my mood, what the beer style is, whether it is an ale or a lager, how finicky the yeast is, or how well the starter I made looks or how well the smack-pack inflated. But I'd say that I'm never too far off from those numbers.

 

[jturman35]

Does aerating the wort after pitching the yeast effect flavors any? I would imagine aerating after pitching the yeast speeds up the process? I am letting my extract kits sit in the primary for month. I'm in no hurry.

 

[Jtk78]

Does aerating the wort after pitching the yeast effect flavors any? I would imagine aerating after pitching the yeast speeds up the process? I am letting my extract kits sit in the primary for month. I'm in no hurry.

As noted above, you do not want to aerate after 12ish hours of pitching the yeast. If you do when you pitch, either just before, just after, or in that 12 hour range, your helping the yeast. If you wait 2 days after fermentation has started, your oxidizing the beer, which can cause an off flavor. Typically oxidized beer can have a wet cardboard flavor.

 

[Miraculix]

Me, Never.

I'll 2nd that!

 

[jturman35]

Gotcha! I don't shake once the yeast is pitched. My very first batch I had an accident and let my only carboy bung fall into the carboy. I ended up having to rack back into the boiling pot to fish out the bung. When I transferred back into the carboy the next day the red Ale was bubbling like crazy. This transferring all took place 1 hour after pitching yeast so I wanted to see if this had any affect on the beer.

 

[Kent88]

I've heard people I trust say that if the beer isn't krausening yet that it is safe to aerate, even if it is 36 or 48 hours since yeast was pitched. If you've got a slow starter (which isn't exactly the situation here, I know), a little extra aeration should be fine. Not much alcohol should be there for the oxygen to react with and the yeasts should be able to scavenge much of the oxygen.

 

[Irishguy42]

@Irishguy42 I haven't completely settled on the numbers, but in this case I'd say that I consider light gravity to be below 1.048ish, and high gravity to be above 1.075.

For me it can vary a bit depending on my mood, what the beer style is, whether it is an ale or a lager, how finicky the yeast is, or how well the starter I made looks or how well the smack-pack inflated. But I'd say that I'm never too far off from those numbers.

Good to know.

Thanks!