BIAB and beersmith mash water volume issues

[strongarm]

So I have 4 all grain brews under my belt. I use a 15G pot for my mash. I have experienced some low brewhouse efficiency....62-65% on my last few batches and I think I may know the issue. Beersmith seems to be giving me a low mash water volume....(my last batch asked for 3.25g of water for 10.5lbs of grain. That seems a little low to me. Shouldn't it be closer to .5G per pound of grain? What mash setting should I have set in Beersmith and what other inputs could be causing the issue?

A seperate question, my next batch is going to be a big stout with about 30lbs of grain (15% ABV, 6g batch) . I think that would be around 15G of water?

 

[daksin]

You should be shooting between 1-2 quarts of water per pound of grain. I think 1.25 is most common, and it looks like that is what beersmith is set to by default, because 10.5lbs @ 1.25 quarts/lb is ~3.28 gallons.

I personally prefer a thinner mash for BIAB, but that's a personal preference, and so I usually mash at 1.5 qts/lb. Are you sparging? Many BIAB brewers do no-sparge as well and just mash with their full volume of preboil liquor.

As for your 30lb grist- good luck is all I can say. Can your bag handle 30lbs + all the water it's going to absorb? I'd calculate for massively low efficiency on that batch. I did a 23lb barleywine which maxes out my kettle volume wise with a thick mash (1qt/lb) and got something like 55% efficiency even with 2 batch sparges.

 

[fizgig]

Beersmith usually tells me 7.7 gallons for a 5 gallon batch BIAB, I think you have some settings you need to change, either your equipment (is it set for a 5 gallon pot?) or your mash type.

 

[KIAKillerXJ]

I never use beer smith for my BIAB calculations, don't know why, just find it easy to do in my head.

Final beer vol+ trub loss + grain absorption (for me it's total grain weight *.1) + evaporation

So for instance for the stout I did yesterday with 17lbs of grain:

5+.75+1.7+1.5= ~9 gals

As far as grain weight, never been an issue with me. Done 40+ always hit my numbers with 70+% or more efficiency