Yeast Help

[Pugs13]

Hello everyone. I brew on a 3BBL system and recently purchased some 7BBL tanks. My process will be to brew batch #1 on day #1 and pitch 3bbl worth of yeast then brew batch #2 on day #2 and rack into same tank. I was told as long as I don't go more than 24 hours between batches I should be fine. My question is, do I need to start pitching more yeast on day #2 or will a 3bbl batch of yeast (from WhiteLabs) act like a giant yeast starter? Would you recommend 3bbl or 7bbl pitch? I think they even make a 5bbl pitch too. After initial pitch, so a 2nd, 3rd, 4th, or even 5th generation yeast...assuming I am feeding or using yeast nutrients how much yeast would you pitch (1000ml - 1500ml or more???)...Also, would you oxygenate both batches? How crucial is it to make sure temp of batch #2 going into the tank is at the same temp of batch #1 that is already fermenting? Any info would be greatly appreciated. Thanks everyone.

[dick murton]

Pitch enough on the first brew to cope with both batches of wort. But aerate the second batch of wort. If you pitch the second brew, you may run into flavour and yeast settlement problems. Lets say you add 200 grams dry yeast per batch currently, I think you will find you will not need to add double this amount for a double batch, but perhaps something like 300 grams. However, to be safe the first time around, I would be tempted to double up and not risk slow fermentation. Depending on how fast / effective your full fermentation is, you can then probably reduce the amount of yeast.

[Junkyard]

I've been double batching 3 bbl into 7bbl tanks for a while now, and my process has worked great for us so far. I pitch enough yeast for all 7bbl of wort on the first batch, then 5 hours later I aerate and pump the second batch in. My logic-- After 5 hours my yeast should still be in the thick of growth phase, so adding more oxygen and wort shouldn't screw with them too much.

In your case It's all dependent on how long your growth phase is, but I would think usually when you come in the next morn the first batch should be in full fermentation. I've never aerated that late into fermentation, but Ive heard its bad to aerate in the midst of fermentation because it confuses the yeast, however I've also heard of a brewery with great results aerating during the midst of fermentation (even for single batches). That part might take experimentation to find out what works best for your process. As far as amount of yeast goes I think I would pitch enough for the full 7 bbl batch. But if it's working good for you now with the 3bbl pitch on the first day keep doing that because it's all about the results you are looking for as a brewery.

[Yeast]

my rule for multiple fills is

the first batch gets all the yeast. yeast only gets pitched in the first batch

you pitch enough for all the brews happening within your lag phase (12 hours is a good rule of thumb)

anything >12 hours out don't include in your pitch rate

oxygenate all brews within 12 hours but don't oxygenate brews that are more than 12 hours out from the first fill