First runnings question

[papagoat]

This weekend I am planning to brew an Imperial Stout and a Stout with some buddies. The plan is for each of us to do 4 identical mashes (20 lb. grain bill each). Take the first 7 gallons off our first runnings and brew a 5 gallon Imperial with a massive 2000ml yeast starter (001). Then take all of our second runnings and brew a large 15-20 gallon (depending) stout. My software doesn't calculate the gravity of first runnings and I honestly don't care. It'll be what it will be (probably massive). I am interested if there's a reason I don't know of why this won't work or anything unforeseen I should watch out for.
Thanks in advance
Papa

 

[duboman]

There is no reason this won't work, basically a partigyle brew process. If you have a refractometer you can take a pre-boil gravity reading pretty quick or chill a sample and read with hydrometer. I know there is a calculation but not off hand.

Keep in mind that a simple 2L starter may not be enough for the first running batch so you'll want to use a calculator to ensure proper pitch rate for a big beer. a 2L starter is not massive by any means unless you are using multiple packs of yeast in it.

 

[papagoat]

There is no reason this won't work, basically a partigyle brew process. If you have a refractometer you can take a pre-boil gravity reading pretty quick or chill a sample and read with hydrometer. I know there is a calculation but not off hand. Keep in mind that a simple 2L starter may not be enough for the first running batch so you'll want to use a calculator to ensure proper pitch rate for a big beer. a 2L starter is not massive by any means unless you are using multiple packs of yeast in it.

Thanks so much for the advice. I use a magnetic stir plate but that is the largest beaker I have. If I let it run 48 hours instead of 24 will I get more cells or would they start to run out of sugar? I have refractometer. Is there a gravity that is too high. If it pops at 1.1 will I be ok. This will be my biggest beer by ABV ever.

 

[Bobby_M]

This is pretty easy to figure out.

20 pounds will soak up 2 gallons of strike water so if you want 7 gallons of first runnings, you'll use 9 gallons of strike water. 20 pounds of grain, assuming about 35 PPG is 700 points of sugar diluted in 9 gallons. 700/9 = 1.078 gravity.

Did I misunderstand that each person is using 7 gallons or you're all contributing 1.75 gallons each to make one 7 gallon big beer batch?

If that's the case, you'll want to mash thicker. The lowest realistic strike volume would be something like 20qts/5 gallons. In that case, each first runnings will be 700/5= 1.140 preboil per brewer.

 

[duboman]

This is pretty easy to figure out. 20 pounds will soak up 2 gallons of strike water so if you want 7 gallons of first runnings, you'll use 9 gallons of strike water. 20 pounds of grain, assuming about 35 PPG is 700 points of sugar diluted in 9 gallons. 700/9 = 1.078 gravity. Did I misunderstand that each person is using 7 gallons or you're all contributing 1.75 gallons each to make one 7 gallon big beer batch? If that's the case, you'll want to mash thicker. The lowest realistic strike volume would be something like 20qts/5 gallons. In that case, each first runnings will be 700/5= 1.140 preboil per brewer.

Thanks for chiming in, couldn't remember the math!

As for the stir play/starter-no running longer will not grow more cells, plug Bobby's OG number into Www.yeastcalc.com and you will see the required pitch rate. You'll definitely need a stepped up starter!

Run the first step, crash and decant and then a second step, or have someone else run another starter with more yeast and combine them at pitch.

 

[papagoat]

This is pretty easy to figure out. 20 pounds will soak up 2 gallons of strike water so if you want 7 gallons of first runnings, you'll use 9 gallons of strike water. 20 pounds of grain, assuming about 35 PPG is 700 points of sugar diluted in 9 gallons. 700/9 = 1.078 gravity. Did I misunderstand that each person is using 7 gallons or you're all contributing 1.75 gallons each to make one 7 gallon big beer batch? If that's the case, you'll want to mash thicker. The lowest realistic strike volume would be something like 20qts/5 gallons. In that case, each first runnings will be 700/5= 1.140 preboil per brewer.

We are all doing a 20 lb mash so we'll each donate 1.75 gallons of first runnings. Thanks for the target number of 1.140. That's a beast! Our second runnings are going to make a second beer. Awesome help. Thanks!

 

[papagoat]

Thanks for chiming in, couldn't remember the math! As for the stir play/starter-no running longer will not grow more cells, plug Bobby's OG number into Www.yeastcalc.com and you will see the required pitch rate. You'll definitely need a stepped up starter! Run the first step, crash and decant and then a second step, or have someone else run another starter with more yeast and combine them at pitch.

Wow. I have a second beaker. I'll make 2 starters, one just won't have a stir plate.
Thanks again!