All grain brew no. 2 – russian imperial stout & porter (2-in-1 batch)

by Daniel on July 2, 2012

The most recent batch of beer I brewed was ambitious, which also made it a great learning experience for me when I ran into trouble.  As my goal has been to share my mistakes & successes along the way, I think this is the perfect experience to walk you through step by step so you can avoid the same mistakes I did.  Sure, you may make different ones, but that’s why we keep brewing is to get better, right?  Further, I’ll show you how to get two different beers from one batch of grain.

I found the recipe for a Russian imperial stout on Home Brew Talk’s recommended recipe database, which is a great resource for any home brewer.  Since I am not yet ready to reinvent the wheel with every beer I make, it’s a great way for me to get a lot of brewing repetition in while making beers I will enjoy.  Here is the recipe I followed – so if you’d like, you can do it yourself.  I also found that a few people used the same grain from the imperial stout, sparged a second batch of water through and made a porter to boot!  Especially when you are buying 21lbs of grain and a ton of hops for such a big beer, it’s nice to be able to get a second 5 gallon batch out of the deal to offset the cost.

To see how I messed up my mash efficiency, what I did to recover, what I’ll do to prevent the same problem next time, and to learn how to get two beers out of one, keep on reading!

Fly Sparging Russian Imperial Stout

fly sparging

After I had all of my mash water prepared and had pre-heated my mash tun, I immediately made my first and biggest mistake without knowing it:  I added the grain to the mash tun before the water.  This wasn’t a problem with my first all grain batch because it was a lot less grain so it mixed more easily with the water.  The problem I had after adding the water this time was that my mash tun was full to the brim and it was difficult to stir all 21lbs of grain.  What I didn’t know was when I was working so hard to stir my grain, I displaced my flexible false bottom by scooping it up with the spoon, and it stayed there when the grain bed settled.

What this meant is that when I used the fly-sparging technique (another mistake), the water didn’t filter through all of the grain before going out to my boil kettle – it drained early out of the portion that was higher in the grain bed.  Had I used the batch-sparge technique, this would not have been a problem as all the sparge water would have time to soak with the grain.  I ended up not getting all of the sweet sugars out of the grain I spent so much money on!  Since I did the same thing with my second runnings and didn’t realize the problem until I had completely drained & dumped the grain bed, my 2nd beer had similar problems.  So to prevent this from happening again I’ve decided on two things:

  1. Add the mash water to the mash tun before the grain – this will make for a more even mixture and require less stirring (less risk of displacing my false bottom)
  2. Batch sparge – while some people say you lose some efficiency with fly sparging vs. batch, the effect is really minimal when considering home brew batch size, especially 5 gallon batches.  Plus, in this case it would have hugely improved my efficiency!

So how did I know I’d made a mistake and how did I fix it?  Luckily I was using my own excel spreadsheet (now available if you subscribe to my blog in the side bar on the right) that I use to make all of my on-the-fly calculations which I designed based on the methods presented in Ray Daniels’ Designing Great Beers and John Palmer’s How to Brew.  I took a gravity measurement from my first wort of 1.042, adjusted the calculation based on the effect of temperature (176F) on the density, and got an estimate of 1.080 estimated OG after the boil from 6.5 gallons down to 5.5 gallons.  Being that my OG was supposed to be 1.106, I knew I was in trouble.  Fortunately I also knew that if I added a certain amount of dry malt extract (DME) I could make up the difference.  My calculator helped me do the rest effortlessly, and I figured out that I needed to add 3lbs of DME to fix the issue.  Sure, I was sad that I hadn’t done things right, but it’s nice to not be completely helpless and just have to compromise and continue with a 1.080 beer rather than 1.106, or to be ignorant to the problem until I measured the OG at the end of my boil & cooling.  So if you’re looking to up your game, I highly recommend Ray Daniels’ Designing Great Beers.  It definitely saved me this time!

"Cool 2nd Runnings Porter"

my fermenting porter

When making such a “big” beer with so much grain, there’s going to be sugars left in the grain that you don’t get in your sparge for your first 6 gallons or so.  So why not run another 6 gallons of sparge water and see what you get?  It certainly can’t hurt other than the time to heat up all the water.  I was a little surprised when I took the second runnings with more sparge water for a porter that I pretty much hit the gravity I expected.  I estimated an OG of 1.033 or so, so by I adding 1lb of DME to the boil I bumped it up to 1.044 which is in the range for a porter.  For hops I chose Fuggle, 1.5oz at the start of the boil, and 0.5oz with 5mins left in the boil.

The rest of the brewing went off without a hitch and I hit my original gravity for both the imperial stout and the porter, pitched my yeast and took them to the basement to ferment at the ambient temp of 67F.  Don’t forget that when brewing a big beer like an imperial stout that you either need to make a yeast starter or pitch two yeast packs.  I made a 6 cup yeast starter and took 1/3 to pitch to my porter and 2/3 to pitch to my imperial stout.  Both started happily bubbling quickly – the imperial stout actually was bubbling within 6 hours, and the porter I suspect sometime later that night.

Hopefully you picked up a few helpful pieces of information from this, I certainly learned my fair share from this experience!  To see more, check out some of my other brewing attempts.


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