BIAB water to grist ratio calculator help

[thehopthief]

I typically follow biabcalculator.com for my mash volume when brewing my beer. Recently I've started to investigate why my efficiency has been really low 60% or less and maybe more important, very inconsistent. I got some good advice to try to mill more fine which I will ask tht brew store to do and do longer mash times but i was listening to a podcast interviewing the guy who owns brew in a bag.com and they were discussing water to grist ratio being most important to efficiency so I looked into it.

My goal last beer was OG 1.074 with 13 lbs of grain and all calculations done in brewfather app. The ideal grist to water ratio per the podcast and now my own research is 2.6-3 qts/lb. This means for 13 lbs of grain you want 8.45 gallons. Then with grain absorption of 0.04 gall/lb I'd lose 0.52 gallons so preboil volume of 7.93 and with boil off and trunk get 6.43 gallons in fermenter.
However I really only wanted 4 gallons in the fermenter so when I tell biabcalc this it tells me my water should be 6.02 gallons. This is a ratio of 1.85 qts/lb which is really low but then the numbers fit for what I expect in the fermenter.

Clearly I'm missing something here. How can I maintain a good water to grain ratio and still get the right volume calculation? Almost definitely a dumb question but I'm new and trying to figure out this efficiency issue.

 

[IslandLizard]

Although you could mash longer and stir well a few times while the mash is progressing, to help with more thorough conversion, the best ways to increase mash efficiency are:

#1 - Finer milling:
The mesh bag is your filter, so it can be milled almost to dust. A gap of 0.025" will get you a great BIAB grist. Most LHBS mill gaps are set to 0.045" to 0.055". Yeah...
It's easy to see why milling twice won't cut it either. Even worse when small kernel grain is included (like malted wheat, rye, or oats).

#2 - Sparging:
In combination with #1. Much high gravity wort remains trapped inside the ball of wet grist in the bag. A simple dunk sparge in a bucket holding a gallon or 2 of water will dissolve/extract much of that. A second sparge gets you a few points more.

Mash thickness (qts/lb) is not the main driver of good mash efficiency.

 

[thehopthief]

Although you could mash longer and stir well a few times while the mash is progressing, to help with more thorough conversion, the best ways to increase mash efficiency are:

#1 - Finer milling:
The mesh bag is your filter, so it can be milled almost to dust. A gap of 0.025" will get you a great BIAB grist. Most LHBS mill gaps are set to 0.045" to 0.055". Yeah...
It's easy to see why milling twice won't cut it either. Even worse when small kernel grain is included (like malted wheat, rye, or oats).

#2 - Sparging:
In combination with #1. Much high gravity wort remains trapped inside the ball of wet grist in the bag. A simple dunk sparge in a bucket holding a gallon or 2 of water will dissolve/extract much of that. A second sparge gets you a few points more.

Mash thickness (qts/lb) is not the main driver of good mash efficiency.

So when you sparge do you set the water profile in the full kettle then take like 2 gallons out? That might help me actually be able to fit bigger beers into my 10 gallon pot too

 

[rburrelli]

Seems like you are doing full volume BIAB. No sparge. That inherently is less efficient than sparging.
Typical ratio for sparging would be between 1.5 - 2 qts/lb.

 

[IslandLizard]

So when you sparge do you set the water profile in the full kettle then take like 2 gallons out? That might help me actually be able to fit bigger beers into my 10 gallon pot too

That's right.

Just be aware of how strike temps, gravities and such are calculated. You want those based on your actual strike water volume used.

 

[thehopthief]

That's right.

Just be aware of how strike temps, gravities and such are calculated. You want those based on your actual strike water volume used.

Thanks I'll keep that in mind. So what temp do y'all sparge at? I keep seeing 170. Is that a rule of thumb?

 

[IslandLizard]

Thanks I'll keep that in mind. So what temp do y'all sparge at? I keep seeing 170. Is that a rule of thumb?

For fly sparging yes, but not for batch sparging.

You would be doing what's considered a batch sparge, and you can do that with water at any temp, basically, even cold water. Now I think warmer/hotter water keeps the mash more fluid when lautering, especially when using larger amounts of sticky grist such as wheat, rye, flaked goods. etc.

Since you BIAB you don't need to do a mashout, because as soon as you pull the bag, you start heating the wort toward a boil anyway. It mashes out (denaturing the enzymes) that way.
The wort inside the pulled bag will keep converting for a while, until you dilute it in the sparge vessel (bucket), but most conversion is done already after the hour mash. So during those few minutes the few quarts of wort trapped in the bag won't change much.

Doing a mashout, and thus locking in the sugar profile of the wort it created, is meant and most useful for (3 vessel) fly sparging systems, as it takes an hour or longer to complete. In that scenario you do want to stop the mash conversion by denaturing the enzymes at that higher temp of 170F for 10'.

I don't BIAB, I use a converted cooler mash tun. Toward the end of the mash I heat the needed (batch) sparge water in the boil kettle, and store it in a spare kettle while lautering and filling up the kettle with collected wort. After fully draining the mash, tun, I then sparge 2x, each using half my (reserved) sparge water.