4 day lag, repitch or keep going?

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vash68

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I am not new to lagers ;)
I usually get active fermentation in my 6.5 gal lager batches within 24 hours of pitching yeast (starter or harvested) at most.
This time the lag was 4 days!
Fast Ferment Test had similar 48 hours lag at room temp!

So I bought fresh yeast (same as original, WLP 830) and made 2.7 liter starter (per calc for batch size and temp) and just noticed fermentation activity in the fermenter started!

Any advise on what to do now?
My choices are:

1. I can keep fermentation going with existing "slow" yeast and then deal with excessive diacetyl later by adding fresh starter during D-rest.
2. I can add fresh starter to fermenter now and hope that will help/ eliminate diacetyl problem due to long lag. (should I oxygenate more before pitching fresh yeast?)

3. Any other suggestions?



Here are details on fermentation timing and temps:

Batch 72

1-25-20 7 pm wort temp 50F, SG=1.050, pH=5.39,
I brewed 6.5 gal batch #72 Pilsner oxygenated as usual for 3 min and pitched WLP 830 S. German lager yeast cake at 50F that I harvested 1 day before from my previous lager batch #71. This yeast fermented lager batches 70 and 71 to perfection.


1-26-20 5 pm wort temp 50.1F, no airlock activity after 24 hours. I am warming up fermenter to 52F. Checked all the seals on fermenter.

1-27-20 9 am wort temp 52.3F, no bubbles.
1-28-20 9 am temp 52.3F, no activity in fermenter OR FFT flask
1-28-20 6pm - I bought 2 packages of fresh same WLP830 Yeast and made a starter.

1-29-20 9 am temp 52.3F, 1 bubble/6 sec, it’s alive?
1-29-20 7pm temp 53.0F (getting warmer!), 1 bubble/2 sec, there is definitely fermentation.
SG (refractometer corrected)=1.040, pH=5.01




I have been brewing lagers for 7-8 years, and lagers are 90% of my beers.
I use 14 gal conical fermenter from ssBrewTech inside a freezer, and harvest yeast via bottom dump valve attached to a sight glass.

No idea what caused this yeast to almost die. All opinions are welcome.
Thanks
 
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Bassman2003

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A head scratcher since the yeast is a re-pitch. The only variable left is if the wort has some sort of issue?
 
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vash68

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A head scratcher since the yeast is a re-pitch. The only variable left is if the wort has some sort of issue?
Good guess, I just cant think of any problem with the wort, apart from some infection maybe?
It was mashed at 150F (my usual pilsner grist, only fermentables in the mash) , 90 min boil, lowered to 50F, oxygenated for 3 min.

My bet would be frozen yeast before it was collected from fermenter, but that is a long shot.
I inoculated this batch with the Yeast dump #1 from previous batch #71 which was made at 60F at the end of D-rest. Then after 48 hours, I added Yeast dump #2 and #3 from the same batch #71, which potentially could have sustained some freezing temps in sight glass while I was bringing fermenter temp from 60F to 40F pithing 48hours. However, this was my standard procedure for the past several years and I never had such long lag.
 

RM-MN

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I'd go with number 3, another option. refrigerate the new starter and use it in another batch. It should be fine for a month or more in the refrigerator.
 

Bassman2003

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If the yeast got down to freezing temps, that has to be your issue. No other good explanation. Maybe you have been whistling past the graveyard so to speak with the previous batches?
 

Cavpilot2000

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I always try to keep a few packets of 34/70 on hand for slow starts. If I don't have good activity by 36 hours, I just dry pitch a packet. It has never failed to kick fermentation off within a few hours.

No starter, no fuss - just toss in the dry yeast and boom! Fermentation.
 
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vash68

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If the yeast got down to freezing temps, that has to be your issue. No other good explanation. Maybe you have been whistling past the graveyard so to speak with the previous batches?
LOL, that is a few years and 50ish batches worth of whistling!
Thanks for the idea, I should review my process since I was brewing on autopilot for a few years.
I was reading long time ago that certain temps may cause yeast cells to burst, but I dont remember what temp that was. Do you think is it 32F and below or much lower?
If so, then how people freeze yeast to create slants for long term storage?

Also, when we cold crash, dont we subject our fermenter with yeast in it to below freezing temp for periods of time before it reaches cold-crash temp? And then we either dump yeast from there for re-pitching or pour a new batch directly into fermenter (if non-conical) on top of old yeast?
 
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vash68

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I always try to keep a few packets of 34/70 on hand for slow starts. If I don't have good activity by 36 hours, I just dry pitch a packet. It has never failed to kick fermentation off within a few hours.

No starter, no fuss - just toss in the dry yeast and boom! Fermentation.
Yep, good practice, I used it when I was starting with lager a few years ago. But this time I didnt have any on hand :( Thanks for reminder, will certainly stock up on dry yeast.
 

Bassman2003

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LOL, that is a few years and 50ish batches worth of whistling!
Thanks for the idea, I should review my process since I was brewing on autopilot for a few years.
I was reading long time ago that certain temps may cause yeast cells to burst, but I dont remember what temp that was. Do you think is it 32F and below or much lower?
If so, then how people freeze yeast to create slants for long term storage?

Also, when we cold crash, dont we subject our fermenter with yeast in it to below freezing temp for periods of time before it reaches cold-crash temp? And then we either dump yeast from there for re-pitching or pour a new batch directly into fermenter (if non-conical) on top of old yeast?
I do not re-pitch, so I do not know. I also do not know for sure what your procedure is. Cold ambient air temps and the temperature of wort are often pretty far apart. If you did freeze your yeast, I do not know if they are dead, maybe, but for sure dormant. Hopefully some other will chime in. Though from what you stated, a lot of the initial yeast was from 60f wort. So I do not see a lot of freezing going on.
 
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