Mash vs sparge volumes

[romen]

Hi all, Hoping someone can help me figure something out. I use the Brewfather software and my brew system is the brewzilla 35L. It's one of these if you're not familiar. I don't really get how the software decides to divide the total water volume between mash and sparge, and why it changes it per recipe. Roughly, for a 5 gal. recipe if there's 6 gallons of total water, sometimes it calculates that most of it is mash and a little bit is sparge. But sometimes it has the water split close to 50/50, so only about 3 gallons of mash water. The problem is that that little water only comes up about an inch and a half into the grain basket. I'm not sure, but I feel like mashing in like an inch of water, and then sparging with 3 gallons of water doesn't give me good results. Perhaps contributing to astringency? But then I don't really get how the software is calculating the volumes for each recipe.

[JonW]

I know nothing about the Brewfather software, but likely it is a configuration issue with something either in the recipe or equipment profile. Also, the volumes in each recipe will be different based on changes of the mash bill (qty and grains used), boil time and the total pre-boil volume requested.

You can do an easy sanity check on your recipes by doing your own manual calculation. The general rule for mash thickness is 1.25 quarts of water per pound of grain and 1 pint per pound of loss due to absorption. Use that to get your strike/mash volume and make up the difference in the sparge volume. Remember you also need to add back the absorption loss too.

Here's a quick example for a 6 gal pre-boil volume using 12 lbs of grain.

12 lbs x 1.25 qts = 15 qts (3.75 gallons) for mash
6 gal - 3.75 gal = 2.25 gal for sparge PLUS 12 lbs x 1 pint = 12 pints (1.5 gallons) for sparge
You'll need 3.75 gallons total for sparge to get you back to 6 gallons pre-boil.

[romen]

So the issue is the headspace between the kettle and the grain basket, I'm not sure the brew software understands that. There's a space between the two, so as you pour water into the brewzilla, the first two and a half gallons or so are below the grain basket. And if you're mashing with only three gallons of water, the grains are only immersed in the top half gallon of water. Not sure if that makes sense. You're basically mashing in 2 inches of water, which barely even cover the grains. Would that be an issue?

I brewed my batch yesterday and just made an executive decision to leave more water in the mash and have less sparge water and it seemed to work out OK.

[JonW]

Wow, 2.5 gallons seems like a LOT of dead space (for a 5 g batch). Unfortunately, I know very little about these single kettle systems. You definitely want your grains to be fully soaking during the mash, but just as concerning to me is that all the dead space liquid could be thinning the mash so much that your enzymatic conversion process could be suffering. Again, I don't know much about these systems so maybe that isn't a real concern here.

Is this a recirculating system for the mash or just steep & stir?
Hopefully Tim or Curtis or someone else experienced with a similar setup can chime in.

[romen]

Yes, it is recirculating, so it is pulling water from the bottom and feeding back into the top where the grains are. And the water filters back through to the bottom through a mesh at the bottom of the basket. So all the water does kind of come into contact with the grains during the mash. I have a gen 3 model, I've heard the newer models have removed the dead space below the grain basket to solve that issue.

[CurtisG]

Not exactly an answer to your question, but I've been doing BIAB as a full volume mash (all the water at once) for the past 5 years and would recommend trying it out.

In my opinion the basket gives us a lot more freedom than a traditional mash. We can stir the grain and not worry about channeling, we don't have to set the grain bed either. Back when I brewed every other week I ran a few experiments regarding mash efficiency where the variables were stirring, full volume mashing, proper grist/water ratio, squeezing the bag, etc. and the only one that had drastic results was stirring. I don't even recirculate anymore. I just full volume mash and stir the grain really well every 10 minutes. I'd give it a shot, it definitely makes calculating recipes easier.

[romen]

That's super interesting. One reason I'm interested in this topic too is my first batch I brewed I had a lot of astringency and haven't totally figured out why. I did stir it a lot and was very aggressive with the sparging. Now I just stir to incorporate all the grains when I first mash in, then set the recirculation and then don't futz with it, and the sparging is minimal. I know lots of people say squeezing the bag doesn't contribute to astringency but I haven't had any issues since. As far as full volume mash, my question there would be how do I set that in Brewfather? Or is it something I just do and leave the software as is.

This last batch, I did measure a noticeable increase in gravity pre and post sparge, so it did extract some more sugars to do that.

[CurtisG]

I never found squeezing the bag to contribute any astringency either. I only get bad astringency based on pH but with full volume mashing everything is very stable since there is so much water. I just shoot for whatever pH I want in bru'n water with 0 for my sparge number.

I'm not sure how to set it up in Brewfather since I haven't used that. I usually use Brewers Friend but I don't use their water numbers, only gravity/ibu/srm etc.

To calculate my water volumes I would start at 6 gallons to account for trub and boil loss, then calculate and add water for grain absorption depending on my recipe. ~0.2 gallons per pound if you don't squeeze the bag. And just dough into that assuming it will fit in my foundry.

https://www.brewersfriend.com/homebrew/ ... -cream-ale

For example here's my cream ale. Start at 6 G, 7.5 lbs of grain that will absorb liquid (corn and sugar will dissolve) is 1.5 gallons of water if you don't squeeze. I usually get a half gallon back squeezing so I'd use 7 gallons of water.

It takes some messing with because it's system dependent but you can really dial it in.

[romen]

Super helpful, thanks!