Very low efficiency -- any ideas?

[Upstate12866]

I have brewed BIAB 4 times now, but I get really bad efficiency each time. What am I doing wrong?

1. I use 1.25-1.5 qt water per pound of basic American pale malt. Today, I did 1 gallon for 2.75 lb of malt. I want to make 2 gallons of light pale ale, maybe 1.038 is my target. By my calculations, that should be about 70-75% efficiency, which I understand is reasonable for biab.

2. Temp after dropping in grains was about 152. Cut the heat and left for 30 min, at which time it dropped to 145. I heated to 158 and cut heat for 30 min. Then mashout by heating to 170. A total of 90 minutes for all this.

3. I squeezed the bag like hell, then ran the other gallon of my warm water through and squeezed again.

4. I ended up with og in the mid 20's, after stirring well and adjusting for temperature (85 degrees). I added .75 lb of DME to get to maybe 1.036.

I think my efficiency is too low or my calculations are screwy. An online calculator put my efficiency under 50%.
What am I doing wrong? Any help would be awesome. Every time I brew there is some inexplicable curveball that is throwing me for a loop. Thank you!

 

[camonick]

Most efficiency problems associated with BIAB are related to your grain crush. If you have a good bag, you can get away with a relatively fine crush. I crush my own grain with a Cereal Killer set about as tight as it will go and consistently get mash efficiencies in the low to mid 80% range.
How well are your grains crushed?

 

[Upstate12866]

i wouldn't know if the grains are crushed well or not, unfortunately I ordered them pre crushed from an online store. But that is a variable that would also explain the run of low OG outcomes. I can attach a picture tomorrow if visual aid is helpful. I would love to know for myself what a fine or good crush looks like for biab.

 

[camonick]

i wouldn't know if the grains are crushed well or not, unfortunately I ordered them pre crushed from an online store. But that is a variable that would also explain the run of low OG outcomes. I can attach a picture tomorrow if visual aid is helpful. I would love to know for myself what a fine or good crush looks like for biab.

Most online stores crush for the traditional 3- vessel guys and isn’t nearly fine enough for BIAB. Some stores let you specify double crush or something similar. If you’re serious about sticking with it, investing in your own mill will be something to strongly consider. Then you can order your grain whole (it keeps better and is cheaper) then crush it yourself to your own specifications.

 

[Sunfire96]

I'm also new to brewing, and just started looking into BIAB for small batches. Isn't it usually done at full mash volume, or a small sparge over the bag of grains? That would mean much more than 1.5 qts/lb of strike water. I might be very wrong about this

 

[Gnomebrewer]

It's most likely the crush. Using the grain quantities and water volumes you listed, you should get around 80% mash-lauter efficiency without squeezing the bag and without a sparge - simply using a full volume mash and gravity draining the bag. That's your efficiency into the boil - any trub left behind in the kettle will reduce your brewhouse efficiency. Squeezing the bag and sparging should improve that to 90% or better. Crush is most likely the issue (unless there's something majorly wrong with your water or temperatures). Even if it's crushed decently for recirculating, efficiency would be a lot better than 50%. I bet there were whole uncrushed grains in there! FWIW, when you get a fine crush for BIAB, you'll probably find you're better off batch sparging (put the grain bag in a second bucket of water, stir and drain) rather than trying to run water through the bag (fly sparging) - the fine crush will make the sparge water run down the sides.

 

[MikeCo]

I'm also new to brewing, and just started looking into BIAB for small batches. Isn't it usually done at full mash volume, or a small sparge over the bag of grains? That would mean much more than 1.5 qts/lb of strike water. I might be very wrong about this

You Are correct. BIAB is generally done full volume which equates to a much thinner mash than the OP is using. This may contribute some to low efficiency, but I agree the crush is more likely the problem. You can ask the shop to mill the grains twice if they won’t do a finer crush for you. I have found that stirring the mash every 15 or 20 minutes helps also.

 

[Upstate12866]

What do you guys think of my grain crush?

Also at the risk of a dumb question, what if I ran these through a coffee grinder or blender? It would probably turn the grains to near dust if I let it. I have a couple all grain kits left after this. Thanks

 

[Gnomebrewer]

Very poor. It's hard to tell from a photo though. Those whole looking kernels.....do they break apart if you rub them between your fingers? If they don't they're un-crushed and you'll extract very little from them in brewing timeframes. I'd be asking for a refund if they're un-crushed. If they fall apart then they're crushed, but very coarsely. Either way, one option is to go and buy yourself a cheap corona (corn) mill. You should be able to pick one up for under $20. Run the grain through that to get a fine crush. If the grains are crushed but very coarse, adding a 1 hour step at 160 with lots of stirring should boost your efficiency. Personally, I'd spend the $20!

 

[Gnomebrewer]

You could run them through the coffee grinder, but for the time taken it's easier to get a corona mill.

 

[camonick]

As @Gnomebrewer states above, it can be kind of hard to tell from a photo, but I agree that is a poor crush for BIAB.
I had a couple ounces of unmarked grain in a baggie, so I ran it through my Cereal Killer. Here is what I use in my BIAB rig with a Wilser bag. I do 5 gallon full volume, no sparge and like I said above, I consistently get low to mid 80% mash efficiency.

 

[Upstate12866]

Wow now I see the difference! My grains aren't totally whole but don't look anything like those.

I will buy a Corona grinder. Does anyone have any tips on a cheap one that works for them? The knock offs I see on Amazon seem to have a problem with being painted silver, leaving paint chips in the grain. If you happen to know of one I would appreciate the lead. Thanks a lot for everyone's help!

 

[MikeCo]

What do you guys think of my grain crush?

Way more coarse than I use for BIAB.