BIAB efficiancy question

I'm thinking about simplifying and trying a no sparge batch next time around. I've been getting about 78% efficency with a batch sparge. How much should I need to boost my grain bill due to the slight efficiancy losses due to skipping the sparge? And do you just mash with your total water amount and not worry about the fact that it's going to be an extrememly thin mash?

Yes, it's a full-volume mash. If you stir well and squeeze the bag intensely I think you can still get pretty good efficiency. Of course, it wouldn't hurt to have a gallon of sparge water handy to just pour over the bag while it's suspended from the BK.

Basicly the difference will be the slight due to the higher levels of sugars that are left absorbed into the grain. As said above, squeezing will minimize this, but as a guess if you just drain the bag well, maybe a couple, three points, not much. I just let the bag drain well and call it good, I have attempted squeezing, but it can be messy and not worth it as I am brewing indoors. If you want to boost your grain bill by 3-5%, it should be a wash I'd imagine.

I don't know if it's truly logrithmic, but it's certainly not a linear decline in efficiency as your OG increases.
A 1.050 wort may lose 3-5 points, a 1.075 beer might lose 15 points.

Full volume BIAB efficiency is directly dependent on the liquor:grain ratio in the mash.

Not sure of the exact curve, but as your l:g ratio drops the mash gravity increase, and as the grain absorption remains constant (by weight) you lose relatively more sugars. This is basically a "lautering loss"

Think it's time I ran the numbers and made a chart

Thanks, Im just going to have to try it out and see what i get, Ill start by boosting grains about 5%

stux said:

Full volume BIAB efficiency is directly dependent on the liquor:grain ratio in the mash.

Not sure of the exact curve, but as your l:g ratio drops the mash gravity increase, and as the grain absorption remains constant (by weight) you lose relatively more sugars. This is basically a "lautering loss"

Think it's time I ran the numbers and made a chart

Click to expand...

I ran the numbers and made a chart

My discussion on this chart : http://www.biabrewer.info/viewtopic.php?f=74&t=1481

Basically, I've graphed the Lautering Loss as a percentage vs Liquor to Grain Ratio for four True Absorption values.

1.2 L/KG = BIAB Heavy Squeeze
1.3 L/KG = BIAB Medium Squeeze
1.4 L/KG = BIAB Light Squeeze
1.56 L/KG = Traditional Mash Tun

As modelled using my Conversion Efficiency formulas, which have been quite successful in modelling the BIAB process

This is for No Sparge. You can see why a sparge makes a big difference when the L:G is low.