First 10 gal BIAB low gravity

[arrasmithf]

Need help figuring what I did wrong. I have several successful 5 gallon BIAB batches so I thought I knew what I was doing. Today I tried my first 10 gallon batch and way undershot my gravity. I followed the same process I normally do so I'm not sure where it went south. Grain bill was 19 lbs. Beer Smith showed a really large volume of water (57qt) too much for my 15.5 keggle so I used a different online calculator and used 48 qt. Instead. Heated to 160 strike temp(took a good bit longer). Mashed in and first thing I noticed was too much water and overflowed the pot. After that, I hit mash temp 152 and rested for an hour. Mash temp held and I didn't have to fire again. I pulled the bag with my pulley hoist no problem. I let the bag sit above pot while I heated the keggle to boil. Pre boil Target was supposed to be 1.044 but temp adjusted gravity was only 1.034. I tried to squeeze but was not as easy as a 10lb bag. added ingredients and boil for hour. At 1 hour I took another sample and was only at 1.040. Level was at about 10 gallons so I didn't want to boil longer. I had 1 lb of Candi syrup from another batch so I tossed it in and gained a few points. Finished at 1.044 and put 9.5 gallons into fermenter. Best case scenario I think I will have 4.5% abv. That's acceptable but I would really like to improve my efficiency without sugar additions. is there something I need to do different for 10 gallons or was it just a fluke. I did read about doing a double crush to improve BIAB efficiency. What do other 10g biab-ers do? Is BeerSmith correct at 57qt?

 

[jdauria]

I don't do 10 gallon batches, but my advise...definitely double crush the grain and stir the mash more over that hour mash rest. What was your mash efficiency with 5 gallon batches with a single crush?

While not really needed with BIAB, I usually still do a mash out for 10-15 minutes. And while I am raising the mash temp up to 168, I stir the heck out of the mash..which further helps to release the sugars. With single crushed grain, your husks were probably too large and then using less water, the water was not able to get to all the sugar in the grain...that's where stirring at least twice during the hour rest comes in in handy. Single crushed grain is too thick (assuming you did not do it yourself at a low mill setting) as when shops do it, they are just breaking the husks open...for BIAB, you want a real fine crush.

 

[RM-MN]

If you are buying your grain pre crushed for you, someone may have changed the setting on the mill. If you plan on doing more 10 gallon batches it would be wise to buy your own mill so you get to control the crush since the crush of the grain is the single most impotent component of good efficiency.

You don't "need" a real fine crush for BIAB but BIAB allows it and that will increase your mash efficiency. I mill my grains real fine with a Corona mill and have come to expect upwards of 80% brewhouse efficiency. I also do a sparge to overcome equipment limitations which increases efficiency also. Since you used a hoist for the bag of grains you could just do a pour-over sparge. Letting the bag hang and drip out will get most of the wort out of it without needing to squeeze.

 

[balrog]

You'll have to get a handle on your volumes. BeerSmith is only as good as your tweaks to it for your equipment, and includes grain absorption which will depend greatly on crush, squeeze, drip time after mash, etc. The thing that stuck out to me in your narrative was the overflow. So you need to get a handle on volumes.

 

[mirthfuldragon]

You can always drain out the first runnings and then sparge to rinse out the extra sugars. Making some inferences, it looks like your pre-boil runnings were a bit short anyway, since you only had 9.5 net to fermentor. When I do high gravity BIAB (or larger batches), I will mash to capacity, then drain into a bucket, then do a batch sparge to hit my pre-boil volume.

Also, depending on the style, you could throw a high-attenuation saison or belgian yeast to finish at 1.005 and still hit your ABV target. And there's nothing wrong with session ales anyway.