Mash/Sparge Volumes for big beer

I'm going to be making a big imperial stout (~12.5% abv) soon, and I'm having a tough time with my water calculations. I use Beersmith for my recipe formulation, and I have the following criteria for this batch:

Recipe size: 6 gallons
lbs of grain: 24.375
Boil length: 120 minutes
Mash tun capacity: 13 gallons

Beersmith recommends I use 30.97 qt of water for the mash (1.25 lbs/qt ratio). Then, I would drain my mash tun and do a batch sparge with 3.55 gal water.

With other beers that I've done, I'm used to having a thinner sparge than my mash. With only 3.55 gal for my sparge, I'm concerned the sparge will barely contribute anything to the beer.

Is this normal? Should I expect to have a smaller sparge as the abv of my beer increases?

arringtonbp said:

I'm going to be making a big imperial stout (~12.5% abv) soon, and I'm having a tough time with my water calculations. I use Beersmith for my recipe formulation, and I have the following criteria for this batch:

Recipe size: 6 gallons
lbs of grain: 24.375
Boil length: 120 minutes
Mash tun capacity: 13 gallons

Beersmith recommends I use 30.97 qt of water for the mash (1.25 lbs/qt ratio). Then, I would drain my mash tun and do a batch sparge with 3.55 gal water.

With other beers that I've done, I'm used to having a thinner sparge than my mash. With only 3.55 gal for my sparge, I'm concerned the sparge will barely contribute anything to the beer.

Is this normal? Should I expect to have a smaller sparge as the abv of my beer increases?

Click to expand...

Also, am I losing efficiency by having such a low sparge volume?

Assuming your first runnings are a 45% yield (typical for myself) of your strike volume (~3.5 gal) plus your 3.55 gal of sparge water (remember, the grain is at max absorption, so whatever volume you sparge with, you should get out of the MLT), that puts you at a pre-boil volume of ~7gal. Now Im not sure what your boil off rate is, but make sure 7 gal is adequate enough to yield your desired pitch volume after a 120 min boil. If it is not, you can sparge with more water to account for the boil off.

You will get that with big beers because the grain bill drives a much larger mash volume of water so there is not so much left for sparge. And yes, your efficiency will be lower when making big beers. So you should knock off 4 or 5% on the estimated efficiency in your calculations so you add more grain to make up for it.

One other option is to calculate it out as a no sparge beer. So you would add more grain and mash water so you get your entire boil volume on the first running. Beer smith will calculate a no-sparge beer to give the correct numbers. Then sparge with 6 or so gallons to make a smaller beer, a parti-gyle, Based on the preboil OG you can calculate how much you need to boil to hit the OG you desire for the small beer.

Do a no sparge. Add the total amount of water needed for the mash. Then drain all the wort, dump it back into the grain bed and drain again.

Wow, there are so many options when making these Imperial Stouts and I've only explored a few of them so far...

24.375 lbs/grain x 1.25 qts/lb*grain = 30.468 qts of H2O divided by 4qts/gal = 7.61 gal. (You need to subtract for the absorption of water by the grains and water weighs approx. 8.3 lbs/gal so divide 8.3 into 24.375 and you get 2.93 gal lost) So 7.61 gal - 2.93 (loss) = 4.68 gal net (1st runnings)

Those are the calculations I use when batch sparging. Ultimately what I am shooting for is a 50/50 split for 1st and 2nd runnings. So in your example above I would shoot for sparging with another 4.68 gal to arrive at the preboil volume. You are are definitely going to have a LOT of wort to boil! I don't know what your kettle volume is but doing a batch sparge on an imperial stout is tough with say a 10gal kettle.

I've done it on my own 10 gal system this way: I capture the 1st runnings into a 10 gal kettle and get it boiling. Then I drain the second runnings into a second (older 8 gal) kettle and get it boiling. When the total volume of both kettles has boiled down to approx. 8 gal I combine them into my 10 gal kettle. Then I proceed as normal like a 60 min boil etc...

It works well for me... I've done this a few times now and have been getting better results each time. It's really tough to plan for these Imperial Stouts! I am assuming you have the mash tun volume to pull this off, hopefully your boil kettle(s) can handle all the pre-boil volume you are shooting for, you know what your boil off rate is, and ultimately you will have a volume that your fermenter can accept. But it doesn't end there! Now you have to ferment this mess and THAT adds a whole extra set of problems to work through! The 1st one is hitting the F.G. which in my humble opinion is the toughest part of making an Imperial Stout. (basically what I do is pitch a big A$$ starter and let it peter out... then I prepare a dry champagne yeast and pitch it in, to finish the beer)

I've tried the party-gyle method of making an Imperial Stout but probably won't do it again. Basically I ended up with a 6.5% 1st runnings beer and a 3.5% second runnings beer.

Here is another approach I was considering while trying the party-gyle method above...
Mash in at what ever thickness your mash tun can handle (1.5/1.75 qts per lb etc.) then you fly sparge with enough water to get to your target boil volume. Fly sparging with a cooler, for example, can be tricky. I don't know if you're using a cooler or not but if you are just leave about an inch or so of water above the grain bed while draining and you'll be fine. To avoid disturbing the grain bed you can simply put a lid from a coffee can in the mash tun and pour the sparge water on it.

These big beers are tough... it takes a lot of thought, and then you typically have to wait for ever to see if it turned out ok. I've been brewing with AG for almost a year now and will be attempting my 4th RIS shortly. 1st try was the party-gyle style, second try ended up more like barely wine(9%ABV and sweet), third try I started using champagne yeast and its much improved!(10%ABV and almost dry)

Before I switched to AG I would brew these Imperial Stouts using extract and they were SO easy! Imperial Stouts with extract were the ONLY extract beers that I could make well... go figure huh?!