BIAB mash volume

[irishrover32]

so iv done a few BIAB brews now but im looking at doing bigger batch brews, the problem is my pot is 8.7G which limits me to 4.5G batches due to the large mash volumes related to doing full volume BIAB mashing. my question is why do you always do full volume mash with BIAB and what are the negatvies or downsides to doing partial volume mashing with BIAB and then topping up before the boil? if i done it this way i could brew much bigger batches.

 

[Cider123]

I was limited with a 10 gallon pot for the same issue. I decided that sparging was not for me and wanted to keep doing "true" BIAB with full water volume. I ended up selling the 10 and getting a 15 gallon. I am very happy with this setup. Plenty of room and never a boil over even if I wasn't paying attention. But I'm only interested right now in 5-6 gallon brews.

Why no sparge for me? Less time, less muss and fuss. Just mash, pull bag, set it on a colander, squeeze a few times and done. The belief that sparging rinses out more fermentables from the grains compared to full water volume mash does not hold water. Want to know more? Go to BIABrewer.info I went to that site a year ago. When I went there I truly went to school. I am a more confident brewer in that process because of it. Not as flashy a site as here, but it is the place to learn BIAB. Look into using the BIABacus spreadsheet, and if a guy named PistolPatch gives you advice, consider it golden.

 

[vNmd]

Some people do partial volume mash and top up, some do a sparge at the end to complete the volume. I have done several full volume BIABs (10). My last batch I experimented with a partial volume mash to see what a sparge would do. I did 5 gal mash (10lb grain) and did 2 gal sparge. While one experiment is not enough to draw any conclusions, my OG was a couple points low compared to usually getting a couple points higher. There are many posts here that discuss the grain / liquid ratios and what that means for your mash as well as several discussions on the full / partial volume BIAB. I have another batch tomorrow and I might still do a partial volume, I might go to 6:1 to see what that does for efficiency and OG. I am still learning so I look forward to what others say on the subject.

 

[beernut70]

I used a 9 gallon pot in the beginning and never wanted to be bothered with an additional step. A lot of people do ok with a sparge so give it a try. I bought a pair of PVC gloves from Harbor Freight and squeeze the crap out of the grains so my absorption was really low. I have the absorption set at .05 gal/lb or .2 qts/lb in my spreadsheet. Squeezing tannins out of the grain is a myth. Which allowed me fit a bit more in the pot.

 

[WoodlandBrew]

Efficiency is lower with a partial volume mash. With your volumes I would be surprised if you loose more than 10% in efficiency. If you tried to mash more than 14 lbs of grain in 4 gallons then you would start seeing significant loss. 15 lbs of grain will actually yield less fermentables than 14 lbs in 4 gallons without a sparge. My book and blog have more details.

 

[Oginme]

One thing to consider is to do a mash with the maximum amount of water you can reasonably fit into your pot. After lifting the bag, put it into a colander on top of the pot and rinse the grains through the bag with the water needed to top off to your desired boil volume. This should help regain some of the efficiency lost by doing a concentrated mash.

 

[irishrover32]

how come the effeciency goes down when the water to grain ration goes down, i thought the optimum consitency for a mash was a porrdige like consitency, guidline ratios are usually 1-1.5 quarts to 1 pound of grain, so how come people here find its better to have a watery mash for BIAB as oppose to a porrdige like mash which i thought was the best?

 

[WoodlandBrew]

Laughtering efficiency is determined by the ratio of water drained to total water added. The more water you add, the less sugar is trapped with the grains due to absorption.

Laughtering Efficiency = wort drained / water added to mash

 

[jtratcliff]

Can I mash it?

http://www.rackers.org/calcs.shtml

I've found their mash volume calculator to be fairly accurate.

 

[laserghost]

the problem with reducing the volume of your mash water because of kettle limitations is that you are going to be mashing at a thicker grain:water ratio, and thereby reducing your mash efficiency into kettle. so the less water you use, the more grain you will need to use.

check out the BIABacus, which has some options for alternatives to full volume mashing. i recently did one where i was able to max out my kettle at the boil volume by reserving water from the mash to top up the kettle with. the downside being a drop in efficiency, but the BACUS scales your recipe on the fly.

 

[Cider123]

You can think in terms of simple diffusion. Sugars (or any molecules) will tend to move from an area of high to low concentration. The more water you use, the more dilute the solution, the greater the diffusion of sugar from high(grains) to low(solution outside grains) concentration. This diffusion will continue to occur until equilibrium is reached, which would take longer or not at all with greater amounts of water.