When to aerate

[PaulStat]

I didn't really get an answer to this before. So I'll make it nice and simple

1. Sparging to the HLT, aerate? Yes/No
2. Transfer from HLT to boiler, aerate? Yes/No
3. Boiler to FV, aerate? Yes/No

Thank you

[Reg]

Errrm... I aerate just prior to pitching, normally by dint of allowing a little drop from the cold break into the fermentation vessel.

[hoppingMad]

1) no,
2) no,
3) yes.

[clogwog]

1. No
2. No
3. Yes, but only when you have the wort down to temperature and are ready to pitch your yeast.

With our local temperatures in Aus, and consequent ambient water temperatures, I have trouble chilling my wort down below 25ºC, even in winter, so I drain it into the fermenter without splashing, and leave it in my beer fridge overnight. Next morning it is down to 18ºC. I then aerate with an aquarium pump, and pitch my yeast. That's for ales and wheats, I only brew 1 lager a year at most.

[Gurgeh]

Aeration does not have any negative effect until during fermentation beyond about (OG-FG)/2 at which point you will detect oxidation off-flavours.

at the risk of a spanking by a gent from blackpool:

HSA does not exist unless there is a fault with the malt.

[Northern Brewer]

1. No
2. No
3. Yes, but only once the wort is cooler than 26.5C (80F) otherwise there is risk of oxidation.

http://www.howtobrew.com/section1/chapter6-9-3.html

[edit1now]

I've only had this info third-hand, but I'm told that a young lady in South Africa did her PhD thesis on this, and concluded that the best time to aerate is 16 hours after pitching. Coincidentally this is the same time that many laboratory tests are reacted or incubated for - get it going, go home at 5, go back to work in the morning at 9 and that's where the 16 hours come from.

Most people aerate homebrew at the time of pitching, and it seems to work.

[Aleman]

Not Biting Pete

Aerate on Pitching . . . unless you have a dirty great big wort chiller, then you can aerate the boiling wort as it comes from the kettle, it passes through the chiller as foam, and as the wort cools it absorbs the oxygen (from the air) . . . benefit is that you don't need a 'clean' air supply.

E1N is also correct . . . partially, you can aerate again at 16-18 hours . . . provided fermentation has not yet started properly . . . . although yeast are a great antioxidant when active . . . This is the idea behind dropping, and if you do it early it can be beneficial . . . . do it late and you have a stuck beer.

An alternative to lots of aeration is to pitch enough yeast in the first place