Grain Pound Question

[BiologistBrewer]

Hey everyone,

I wasn't sure whether or not to put this in the AG section or Beginner's section so I chose here.

I first really got into brewing because my career is as such that I am a Molecular Biologist/ Microbiologist (B.S in Biochemistry). The science behind beer really had me interested and I spent most of my first days brewing with coworkers while collecting up and isolating a bunch of different yeast strains (if you don't filter your beer I've probably isolated your yeast). Something rewarding about taking yeast on the brink of death in a bottle and resuscitating it back in the lab.

I have brewed many different batches with coworkers, but I am now taking the plunge and building my own equipment. I am going to make a 5 gallon mash-tun (don't try and convince me otherwise).

Now my question really is two fold.

Being a scientist, I plan on doing quite a bit of experimentation in terms of yeast mixing, hop additions, etc. My question is that with a 5 gallon mash-tun can I lower my grain bill to finish a wort at potentially a 3 gallon batch or even lower? Some of my co-workers are a bit less OCD as I am when it comes to determining these things, and their response is "cram as much grain as we can fit".

I just want to know if it is feasible for myself to be doing smaller batches within a larger mash-tun, or will I be running the risk of loss of efficiency during conversion. Maybe someone has a thread they can point me to?

Anyways, I look forward to sharing my experiences, hopefully I can add some unique perspectives as I have some capabilities others don't with some fancy shmancy machines.

Thanks all and happy brewing.:rockin:

 

[tre9er]

Depends on your tun type. If it's tall, like a drink cooler, smaller will probably be fine. If it was very wide, you might have more of an issue, but probably not much. I mash 9g batches in a 70qt cooler, so plenty of "dead space" in there, and I hit 80% efficiency every time. I mash for over an hour, sometimes 8, but I always hit 80%.

 

[Yooper]

A 5-gallon mash tun is perfect for 3 gallon batches. You can generally fit 12 pounds of grain (with the water) into it, so you could do a 5 gallon batch of up to about 1.060 or so. Or a 3 gallon batch with a higher OG.

 

[johngaltsmotor]

The only problem might be with a very small load of grain.

I know there is an ideal ratio of height to diameter in order to make sure that you get uniform flow through the grains while sparging.

I used to use a 5gallon and due to big beers I upgraded to a 10gallon and I haven't had an issue making 5gallon batches (down to 6lb of grain in a 10gal water cooler).

 

[BiologistBrewer]

Depends on your tun type. If it's tall, like a drink cooler, smaller will probably be fine. If it was very wide, you might have more of an issue, but probably not much. I mash 9g batches in a 70qt cooler, so plenty of "dead space" in there, and I hit 80% efficiency every time. I mash for over an hour, sometimes 8, but I always hit 80%.

Yeah, the tun is a cylindrical cooler. I'm glad to hear that the dead-space isn't too much of an issue.

 

[BiologistBrewer]

A 5-gallon mash tun is perfect for 3 gallon batches. You can generally fit 12 pounds of grain (with the water) into it, so you could do a 5 gallon batch of up to about 1.060 or so. Or a 3 gallon batch with a higher OG.

So instead of sparging with 5 gallons of water you sparge with 3 to end with a correct wort volume? ie for the 5 and 3 gallon batches respectively.

 

[tre9er]

So instead of sparging with 5 gallons of water you sparge with 3 to end with a correct wort volume? ie for the 5 and 3 gallon batches respectively.

work backwards:

desired batch size into fermenter+boiled-off+grain absorption+trub-loss=total water needed.

Typical boiloff is 1g/hr, less if your pot isn't particularly wide.

Grain absorption with a mash-tun is around .15-.19G/lb. of grain.

So you take your recipe, total grain used, find out absorption, add that in with your boiloff and that's the water you need. Mash with half, sparge with half is an easy way to do it.

 

[JABBY]

Well that was my question as well. I did a 10LB grain bill in my 5G igloo. Came out to 1.620 with 4G. boiled down to 2.5G and I topped up to 5G in my fermentor. The OG was 1.54, still fermenting. The grains I used was 8LB of 2row and 2LB of crystal 40. Beersmith said I had 67% efficiency.

 

[BiologistBrewer]

Thanks tre9er this is exactly what I was looking for.