BIAB with a too-small bag

[Mothman]

Would mashing with a bag that's somewhat narrower than the kettle significantly impact the mash efficiency?

I ask as I've had a couple brews where I've fought with the mash to get the target gravity, having to extend for a significant amount of time, and do a lot of stirring. In other brews I've had no real issues.

I had a lightbulb come on, and I'm thinking the couple I struggled with may have been when I used a paint strainer bag rather than an actual grain bag.

The paint strainer is a 5 gallon bag, and is plenty deep enough for my 8 gallon pot, but when grains are added, I have noted that the diameter of the bag is probably about 70-75% of the width of the pot... so there is a significant amount of water outside of the bag, not in contact with the grains.

My other bag, the actual grain bag, is much larger, and fills the kettle.

My initial thought was that wouldn't really matter... the water within the bag still allowed for a relatively thin mash, and I figured the sugars would still extract fine, and then later mix with the rest of the water volume.... but maybe now that I think a bit more, maybe that's wrong, as the volume of water actually "in" the mash, that the recipe and efficiency was built for wouldn't really be correct.

Long question short... does using a BIAB bag that's noticeably narrower than the pot hurt the mash efficiency?

 

[brewgar]

^ Probably.

 

[RM-MN]

If you are doing a full volume/no-sparge brew I would guess that could be a factor. You have a concentrated sugar solution inside the bag and a very weak solution outside. Just a guess but I wonder if you pulled the bag to drain, then dunked it back into the pot and let it drain again if you would get better efficiency, sort of like a dunk sparge. You might have to stir the grains to get the wort to saturate them again during the dunk.

 

[Jayjay1976]

I use Reaves brand 5 gallon paint strainer bags in a bayou 11 gallon pot for every brew and have had zero problems with efficiency. Though the bag seems a bit small to start with, the load of grain stretches the bag out to fill the lettle, and I've loaded it with as much as 15 pounds of grain. I was a little nervous at first about the strength of a disposable bag, but I've never had one burst or tear despite hoisting mine out of the kettle with a noose of rope around the top of the bag then squeezing the grain aggressively between two metal pot lids as it hangs.

 

[SanPancho]

Id say yes. The solution is either a full size bag or to get some recirculation going between the free wort in kettle and the wort in the bag. Maybe a basic recirc pump that dumps right into the bag. Or lift/ drain the bag and then drop it back into kettle a few times to mix the wort, tea bag style.

Pump is nice. I got set up for about $30 with a small high temp food safe pump at 12volts on amazon, and a piece of silicone hose runs it right back into the mash basket. Bumped a few points in efficiency.

 

[Jayjay1976]

Yeah I forgot to mention, I run a continuous recirc throughout the mash to ensure good flow. I have a KegKing MKII ($89 with SS head) and even with the bag filled right to the top with grain, stirring is no problem with the full volume mash. I average about 72-5% efficiency, and have hit as high as 86% depending on mash temps and grain bill. I use an 18" commercial whisk for stirring and breaking up dough balls, in my mind the rounded shape is less likely to snag or poke a hole in the bag than a mash paddle.

Just to be clear, I started with disposable bags with the full intention of eventually buying a permanent one, but have come to appreciate the convenience of just throwing the whole mess out and changed my mind. Until some catastrophic failure convinces me otherwise, I'm sticking with paint strainers.

 

[soccerdad]

You will probably be fine. But do yourself a favor and get a Wilserbrewer bag. I think my original bag probably costs me less than 25 cent per brew at this point. He will custom make the bag to fit your kettle. I would guess that shipping to BC is not an issue. It comes in a small padded envelope.

 

[Mothman]

I do have a larger, proper grain bag. I've just never really thought about it before and grabbed the one closest at hand, and thinking back I was wondering if my two problem mashes had me using the paint bag.

I noted that when filled with the grain the paint bag held sort of a cone shape rather than filling out.

In both problem cases it turned out OK but I had to extend the mash by about 30 minutes and stir a LOT during the last part to get up to target gravity and wondered if the bag was the problem.

Or it may have been completely unrelated.

I may look into buying a wilser bag... Will see... Last i looked into it it seemed pretty pricey by the time I covered shipping to Canada.

In the mean time I'll just make a point of using my proper bag.

 

[Mothman]

Well I did up a batch today, using the large grain bag... And I again had a lousy mash efficiency... About 67%, Instead of the 75% as per my Beersmith estimates.

So I'm back to the drawing board. In my first handful of biab batches I found 75% to be a good estimate for me, was able to get pretty close to target numbers.

Last couple batches have been pretty low.

This time around I decided to throw in a bit of dry extract I had laying around to make up some of the shortfall, hoping if doesn't change up the resulting beer too much.

Anyway... Next time I might order my grains from a different supplier... Maybe the place I've been using has old grain?

 

[jtratcliff]

This sound like crush to me... BIAB get great efficiency with w/ a very fine crush... If you get your grains from a LHBS, double crush... If you crush your own, tighten your gap (that's what she said!)...

 

[Mothman]

The supply shop I've been ordering from double crushes them for me. I think the crush is decent... everything looks crushed, and there is some dust in the bags.

Is it possible that a badly done scaling in Beersmith could cause this, if the grain amounts aren't correct?

I scale by inputting the original recipe amounts, using my own profile (which is a smaller batch size), then using the OG, Bitterness, and color sliders to set to the original recipe's targets.

 

[RM-MN]

The supply shop I've been ordering from double crushes them for me. I think the crush is decent... everything looks crushed, and there is some dust in the bags.

Is it possible that a badly done scaling in Beersmith could cause this, if the grain amounts aren't correct?

I scale by inputting the original recipe amounts, using my own profile (which is a smaller batch size), then using the OG, Bitterness, and color sliders to set to the original recipe's targets.

If the opening of the grain mill is too big it won't help a great deal to run the grains through twice. 67% efficiency stinks. Buy a Corona mill, tighten it up, and watch your efficiency go up, way up. I have trouble believing mine so I set the software to 85% and always overshoot my OG. It's such a drag having to drink that stronger beer.

 

[soccerdad]

There is no harm in mashing longer to get greater efficiency. Try 90 minutes and see what you get.

 

[MadHomebrewer]

Yes the grain needs to move freely in the mash water. I used 5 gallon paint strainer bags back went I did one gallon batches. I now have a brew bag for my keggle and it is plenty roomy for my grain.

 

[Mothman]

Buy a Corona mill, tighten it up, and watch your efficiency go up, way up

I may end up looking into that.

I don't really want to spend more $$ on gear... But if it reduces my grain bill by 5-10 % or more, it would pay for itself.

Might start poking around for prices here in Canada.

 

[Mothman]

Is this the type of mill I'd be looking for? https://www.amazon.ca/gp/product/B000T3ML4G/?tag=skimlinks_replacement-20

 

[wilserbrewer]

Is this the type of mill I'd be looking for? https://www.amazon.ca/gp/product/B000T3ML4G/?tag=skimlinks_replacement-20

Yes

 

[wilserbrewer]

I think the crush is decent... everything looks crushed, and there is some dust in the bags.
.

There should be a lot more than “some” dust or flour, say about 5-10%, which will appear like quite a bit is the crushed grain is in a clear bag.

 

[Mothman]

There should be a lot more than “some” dust or flour, say about 5-10%, which will appear like quite a bit is the crushed grain is in a clear bag.

Ahh, ok, yeah I definitely did not have that much. More like 'dregs' of dust.

I'm on the lookout for a mill, and reading up on mods to mount it to a bucket.

I see this one too, guessing all these types of mills are similar, just different brands. http://www.ontariobeerkegs.com/Victoria_Grain_Mill_p/victoria-grain-mill.htm

 

[Mothman]

On a side note, I also ordered a bag from you last night, Wilserbrewer.

 

[RM-MN]

I use one like this. https://www.amazon.com/dp/B000U5NZ4I/?tag=skimlinks_replacement-20

To keep the grain from being thrown about I slip a gallon ziplock bag over the business end and hold it in place with a pair of clothespins. One hopper full is about right for a bag. That bag is easy to one-hand dump into the pot while you use your whisk to stir it in.

 

[LittleRiver]

...I'm on the lookout for a mill, and reading up on mods to mount it to a bucket..."

I got the Kegco mill, and set it to .025". It has made a huge difference in my efficiency.

Here's a few photos of how I mounted it to a bucket. It's mounted off center, so I can use the hand crank if I need to, but I normally drive it with a 1/2" electric drill.

The arched pieces that go down into the bucket are made from the scrap left over from cutting out the main disc.

 

[Mothman]

I got the Kegco mill, and set it to .025". It has made a huge difference in my efficiency.

Here's a few photos of how I mounted it to a bucket. It's mounted off center, so I can use the hand crank if I need to, but I normally drive it with a 1/2" electric drill.

The arched pieces that go down into the bucket are made from the scrap left over from cutting out the main disc.

View attachment 556743 View attachment 556744 View attachment 556745

That looks pretty slick!