[morticaixavier]

I've got 5.5 gallons of 1.102ish Barley Wine wort in the fridge at home getting down to temp. I drained it out of the kettle into the fermenter at ~80* with a drop of about 4 inches from the spigot to the top of the bucket. Tonight I will whip the bee jee sus out of it with the mix stir before pitching 2 11g packets of s04 properly rehydrated in boiled, cooled RO water at about 90*.

I added a little over a tsp of generic C&B yeast nutrient at T-10 minutes from flameout as well. I had planned to add a bit more than that but that was all that was left as it turned out.

So my question is should I hit it with the mix stir again tomorrow night? or the next night? night after that? or just leave it be?

as an aside, this was the first time I used Sean Terrills partigyle simulator and it worked like a charm. My overall efficeincy was a little higher than I planned (BW was 1.102 when I planned 1.091, small beer was pretty right on, 1.036 instead of 1.040)

the above is not really germaine to the original posted question but I wanted to give props to sean.

[denny]

I wouldn't re-aerate if fermentation has started.

[nateo]

Rousing is a great idea.

Aerating is a good idea too if gravity hasn't dropped much. Adding O2 is only bad if the yeast don't need it.

[rjharper]

I'm sure I read somewhere it was OK to aerate until the SG passed the halfway mark on your planned attenuation.  So if you're aiming for ~1.020 from 1.100 then unless it's past 1.060 I think you should be OK.  I've never tried it though

[nateo]

I'm sure I read somewhere it was OK to aerate until the SG passed the halfway mark on your planned attenuation.  So if you're aiming for ~1.020 from 1.100 then unless it's past 1.060 I think you should be OK.  I've never tried it though

I've read something similar, I couldn't remember what the cut-off is. If it were my beer, my cut-off would be a lot more conservative, maybe more like <20-25% of planned attenuation. I'd aerate if gravity > 1.080-84.

[denny]

I'm sure I read somewhere it was OK to aerate until the SG passed the halfway mark on your planned attenuation.  So if you're aiming for ~1.020 from 1.100 then unless it's past 1.060 I think you should be OK.  I've never tried it though

I've read something similar, I couldn't remember what the cut-off is. If it were my beer, my cut-off would be a lot more conservative, maybe more like <20-25% of planned attenuation. I'd aerate if gravity > 1.080-84.

What I recall is that's it's OK up to 14-24 hours unless there's active fermentation at that point.  And do you really need it?  I've never re-aerated on any high gravity beer and always gotten great attenuation.  Maybe it's better to deal with it up front with a large healthy starter and adequate aeration at the beginning.

[kramerog]

Neva Parker said at the 2012 NHC that if the gravity has gone down by less than half than it is probably OK to reaerate.  Having said that, you could reaerate this evening a couple hours after the yeast pitch while the yeast is still in the lag phase rather than waiting for tomorrow. 

[morticaixavier]

I'm sure I read somewhere it was OK to aerate until the SG passed the halfway mark on your planned attenuation.  So if you're aiming for ~1.020 from 1.100 then unless it's past 1.060 I think you should be OK.  I've never tried it though

I've read something similar, I couldn't remember what the cut-off is. If it were my beer, my cut-off would be a lot more conservative, maybe more like <20-25% of planned attenuation. I'd aerate if gravity > 1.080-84.

What I recall is that's it's OK up to 14-24 hours unless there's active fermentation at that point.  And do you really need it?  I've never re-aerated on any high gravity beer and always gotten great attenuation.  Maybe it's better to deal with it up front with a large healthy starter and adequate aeration at the beginning.

I mainly ask because on the last few big beers I have done i have gotten some slightly hot flavours. I kept the temp down fairly well with a fridge and controller. and they did age out.

Probably I am over thinking this and will just whip it to a froth before pitching and call it good.

Check my math here

Fermentis says at packaging the s-04 has 6X10^9 cells per gramme (is gramme equivelent to gram?).
so two 11.5 gram packs should have;
6X10^9 = 6,000,000,000 X 11.5 = 69,000,000,000 X 2 = 138,000,000,000. Assuming a desired pitch rate of ~300 billion cells for this brew am I still only half way to proper pitching rate even if the yeast are perfect? I do have a third packet and could get more tomorrow but the third packet was destined for the small beer and the brew store is closed on mondays. grrr.

[kramerog]

Your math is correct.  It is low relative to your desired pitching rate. 

[morticaixavier]

Well that's confusing to. Just checked Mr Malty and he says 1.8 packs even if they are a month old. He also recomends >300 billion cells but says that 1.8 packs will deliver that.

I must be missing something here.

ahh well. I guess I will RDWHAHB and pitch the two packs as planned. There is something wonky in my understanding of this whole thing.

[nateo]

Well that's confusing to. Just checked Mr Malty and he says 1.8 packs even if they are a month old. He also recomends >300 billion cells but says that 1.8 packs will deliver that.

I must be missing something here.

ahh well. I guess I will RDWHAHB and pitch the two packs as planned. There is something wonky in my understanding of this whole thing.

If you properly rehydrate the yeast, 2 11g packs will be plenty. If you just throw the yeast in the cool wort, you'll kill 50%+ of the yeast.  BTW, the optimum rehydration temp varies a bit by strain, but most strains will be more like 100-105*, rather than 90*.

You also don't want to use RO water. Tap water would be better. It needs some minerals so the minerals inside the yeast don't get sucked out into the water.

I came across this that I thought was interesting: http://www.fermentis.com/SHARED/Doc_52528.pdf
Viable cells per gram:
k-97 - 1.4*10^10
s-04 - 0.8*10^10
t-58 - 1.8*10^10
s-33 - 1.6*10^10
s-23 - 1.0*10^10
s-189 - 0.9*10^10

[kramerog]

According to this paper, http://www.fermentis.com/SHARED/Doc_52528.pdf, the amount of dry yeast per gram on average greatly exceeds the 6 billion cells per gram.  That's probably the discrepancy.

[nateo]

According to this paper, http://www.fermentis.com/SHARED/Doc_52528.pdf, the amount of dry yeast per gram on average greatly exceeds the 6 billion cells per gram.  That's probably the discrepancy.

S-04, for some reason, only has 8b per gram, according to that. I've always used the 20b / gram rule of thumb, but I guess it makes sense that it may vary by strain, and I'll try to use that info in the future.

[kramerog]

The 6 billion number is what the manufacturer is guaranteeing will be present on the best before date.  It makes sense there could be a lot more when the yeast is fresh and been kept under optimal conditions.

[kramerog]

According to this paper, http://www.fermentis.com/SHARED/Doc_52528.pdf, the amount of dry yeast per gram on average greatly exceeds the 6 billion cells per gram.  That's probably the discrepancy.

S-04, for some reason, only has 8b per gram, according to that. I've always used the 20b / gram rule of thumb, but I guess it makes sense that it may vary by strain, and I'll try to use that info in the future.

I wouldn't necessarily throw out the rule of thumb.  The authors said they had trouble counting the yeast in S-04 because it was so flocculent.