BeerBorg

I like to do BIAB for my smaller, 2.5g batches, because I don't want to schlep the mash tun around for those smaller batches. But I've been having a real time trying to dial in my volumes. As I write this, I'm waiting on an extra 30 minutes to my boil, because the volume is so ridiculously high, I have visible cartoon question marks shooting out of my head. Here's my process, and I would appreciate any insight, tips, or what-have-you to help me get this closer to what I'm looking for.

I calculate 1.25 quarts of water per pound of grain. I anticipate getting about 3/4 of that back with the first runnings. After the mash, I squeeze the grains, and then sparge in enough water to make up the difference for the pre-boil volume. I want to get between 2.5 and 3 gallons post-boil, which means slightly less than 4 gallons pre-boil. Today, I have nearly 5 gallons pre-boil, and while I can't rule out faulty math on my part, I've always had difficulty calculating BIAB volumes. I know with my mash tun, I'm going to get back half of the mash volume in the first runnings, and I can calculate my sparge water/pre-boil volume pretty accurately.

But this process has got me baffled.

Thanks for any hints you can offer.

http://www.simplebiabcalculator.com/

try this calculator if you haven't already.

Also try full volume mash without sparge. I get the same efficiency just by squeezing the bag and letting it drip dry.

Dave what size kettle are you using and how many pounds of grain and how many ounces of hops? I am able to hit my numbers dead on brewing eBIAB, if you enter the numbers I'll crunch them for you using ezBIAB calculator.

You ask hard questions

Gymrat wrote:You ask hard questions

Haha, I know. Sometimes the devil is in the details.

I think this time, I just mis-measured my sparge water and added an extra gallon to it. So I boiled it for an extra hour before the first hop addition, and it turned out just fine.

I do my sparge and boil in a 5-gallon pot, and the mash in a 3-gallon pot. Usually I've got about 6 or so pounds of grain, and it's a little too much for one pot to handle in a full-volume BIAB.

Today's incident just threw me, because I had thought I was dialing in the proper anticipated volume for my first runnings. And I actually think I am, since my post-boil volume was spot-on, as was the OG. I just need to remember to anticipate getting around 3/4 back, instead of 1/2.

Dave, I've had this problem too. What I've been doing is starting with the same amount of water each time, which is intentionally low. This allows me to make five gallons in a five gallon pot, and I check gravity and calculate top off in the fermenter. I'm trying a couple of new methods today, but I'll start another thread.

If that works for you, then great. But I've never been a fan of topping off or even adding DME/LME post-boil, regardless of the numbers. That's just my thing.

I could do a by-the-book BIAB by using my ten-gallon pot, but it's more than I need, and it's heavy, and I'm lazy and don't feel like jack-assing it around for a small batch. I also like the idea of sparging, even though I know BIAB is (again, by-the-book) a no-sparge technique.

Originally, I was a bit flummoxed by the extra pre-boil volume, but came to realize that it's because I'm really squeezing and pressing the grain bag, which I obviously can't do with a mash tun. When I use the tun, I get 50% of my volume back. With BIAB, I get about 75%. I can live with this, and make the adjustments. In fact, I actually made the adjustments today; I just didn't keep good enough count on measuring out my sparge water, and added a gallon too much.

Shoulda waited for the coffee to kick in, or written it down, or something....

I do like Screwy's calculator, but I've found it does give me a bit too much water, probably due to squeezing. Brewtoad does pretty well for me, so I run the numbers twice and split the difference.

Glad you figured out where the issues was Dave. For the time I did BIAB I sparged as well but I always used the same water volumes since my recipes didn't vary enough in grain bills to warrant figuring our absorption rates. Now that I'm using a mash tun I created my own spreadsheet to determine my water volumes and check it against BeerSmith. I knew it had the tool built in to do it but I wanted to understand how those numbers were derived.

Screwy's is higher than the other 3 I look at but everyone's systems are different so once you find the one calculator that works for you, use it. I've found that Beersmith's doesn't work well for my system. Priceless BIAB and biabcalculator.com work for my system when I take the mean of each.

The only calculator I use is the one on my phone. For me, it's just a matter of learning what to expect with each technique. As I mentioned, I already know I'm going to get half my volume back from my mash tun. I'm learning that I get slightly more from BIAB, since I can (and do) squeeze as much as I can. 75% seems about right, and I'll be able to refine it more as I pay more attention to it.