# BIAB dunk sparge efficiency benefits?



## brando (25/5/14)

Hi guys,

I've been out of brewing for a couple of years, but before my break it was popular to be doing a dunk sparge. I was doing it, and believed that my efficiency was better as a result.

I've just been reading over on the BIABrewer forum that the increased efficiency from a separate dunk sparge is pretty much a myth, and that I'm better off saving myself some time and effort and just full volume mash (and do it for longer - say 90 mins instead of 60 mins). 

They are saying that numerous side by side tests have proven it.

Thoughts?


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## brewbienewbie (25/5/14)

I'm interested in this myself, I've just done my first full-volume biab mash after a few years doing maxi-biab with a sparge. It didn't go well - my efficiency was shithouse. I hadn't heard about the 90min thing, maybe I'll give that a crack next time.


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## hathro (25/5/14)

90 min then mashout. Listen to the BIAB podcast in the other thread.


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## brando (25/5/14)

hathro said:


> 90 min then mashout. Listen to the BIAB podcast in the other thread.


I'm interested... but which other thread are you referring to??


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## Bribie G (25/5/14)

I'm still in two minds, been BIABbing for nearly six years now. Pistol Patch would probably shoot me down in flames but:

Full volume BIAB has the mash AND the "sparge" water added at the beginning of the mash. So you end up with a kettle of wort and a bag of spent grain. There's still a small amount of full strength wort left trapped in the grains.

With 3V you theoretically start with the same amount of water at the beginning of the mash, just that you don't use it all at once. You use some for mashing and reserve some for sparging, and end up with a kettle of wort and spent grain.

With 3V you don't sparge to death as this would weaken the wort requiring a longer boil, as well as extracting tannins, but I'd bet that the spent grain left after 3V is not as "sweet" with trapped wort as the spent grain left after BIAB.

so I personally believe that a small sparge of your spent grains, a "dunk sparge" could flush out some useful fermentables, as long as you use water that you have reserved from the initial strike volume.

I haven't heard a convincing argument otherwise, maybe somebody at a systems wars type brewday could taste the spent grain from various systems and post results.

In any case I doubt if the recovery of this "wasted wort" would add more than a couple of points, personally I don't bother dunk sparging but can see the (slight) attraction if you can be arsed to do it.


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## stakka82 (25/5/14)

When I sparge I always get 80%, when don't I get around 70%. Always the same results over about 50 bigw biabs. 

Whether I do it or not depends on how much I need the extra gravity for a given beer and if I can be bothered, which isn't often these days!


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## Bribie G (25/5/14)

Agree, for me a couple of dollars of extra base grain outweighs the hassle of sparging on the side with doubtful extraction rates, plus an extra vessel to clean up. The beauty of BIAB is that it's a single vessel, straightforward method of wort production. I've experimented with lautering, sparging, etc. but I'm into making beer, not tweaking efficiency as part of a pissing contest. B)


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## GABBA110360 (25/5/14)

I usuallty start with 62l for a double batch 46l
I mash in 42l
then dunk sparge in the other 20l at the same mash temp 
then wring the crap out of tha bag and still only get 70 %
but that works for me
biab


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## hathro (25/5/14)

brando said:


> I'm interested... but which other thread are you referring to??


http://aussiehomebrewer.com/topic/79912-biab-legacy-podcast/


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## brando (25/5/14)

stakka82 said:


> When I sparge I always get 80%, when don't I get around 70%. Always the same results over about 50 bigw biabs.
> 
> Whether I do it or not depends on how much I need the extra gravity for a given beer and if I can be bothered, which isn't often these days!


This is the kind of comment I recall everyone seemed to be saying a few years back!

My own efficiency went from high 60's to mid 70's when I changed to dunk sparging. The BIABrewer forum thread suggested that the greater efficiency is just a result of longer mash time, effectively resulting from longer contact of grains with mash-zone temp water - about 30 mins more. But my dunk sparge lasts no longer than 10 mins, and I'm sure that if I do a full volume mash and simply extend the time from 60 mins to 70 mins I won't get 5%+ increase in efficiency. So I'm puzzled!!!


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## Bribie G (25/5/14)

It would be interesting to know what system the "side by side" tests were conducted on vs BIAB.

However having said that, the podcast really crystallised the 90 minute mash idea for me. As BIAB brewers we don't usually think about what happens with other systems, none of our business. However a one hour mash isn't really a one hour mash for 3v and other brewers because they sparge, and during that sparge which can be quite long for a fly sparge, there is still some mashing going on.


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## Phoney (25/5/14)

Personally I've found sfa difference between 60 and 90 min mash times on efficiency. It takes me 25 mins to ramp up to mash out temp so I figure it's almost a 90 min mash anyhow.


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## nzdavea (25/5/14)

No sparge I get around 67-69%, batch sparge 77 deg for 10 min I'm up around 75%. Not too worried about theories, that's what I've found in practice. For a 23l fermenter volume I do a 20l biab mash (60 min), mashout then 14l batch sparge for 10 min.


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## pcmfisher (26/5/14)

Bribie G said:


> It would be interesting to know what system the "side by side" tests were conducted on vs BIAB.
> 
> However having said that, the podcast really crystallised the 90 minute mash idea for me. As BIAB brewers we don't usually think about what happens with other systems, none of our business. However a one hour mash isn't really a one hour mash for 3v and other brewers because they sparge, and during that sparge which can be quite long for a fly sparge,* there is still some mashing going on*.


Except if you do a mash out at after 60mins.


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## verysupple (26/5/14)

I think a dunk sparge is most useful for people like me that can't do a full volume mash (I use 19L BigW pots). Bribie G and others have touched on it, but I think it's because of the limited solubility of sugar. In a full volume mash the concentration isn't as high so the sugar is more easily dissolved leaving less still in the grain. I mash with a liquor-to-grist ratio of 2.67 L/kg, raise the temp on the stove to mash out at 76 C for 10 min, and find a 5 min dunk sparge at 76 C in the second BigW pot gets a lot more sugars out than not sparging. I know from my measurements that this is only due to better lautering and I'm not getting any more conversion during the sparge.

On the 60 vs 90 min mash thing, it depends what mash temp and grain I'm using. Sometimes I need 90 min to get full conversion, sometimes it's good after 30 min.

Anyway, I'm sure that efficiency increase from dunk sparging with BIAB is not a myth. However the gains will vary depending on your setup. Maybe it's a negligible gain if doing full volume mashes and that's why the BIABrewer tests showed no improvement. This is just conjecture, though, as I haven't actually read their material.


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## stux (26/5/14)

To get the most benefit from a dunk sparse you need to optimise the size of your main mash and your second dunk sparse mash. 

There is definitely an efficiency gain, and sometimes you just can't add more grain to compensate, once you get to a certain l:g ratio you hit less than 50% efficiency and at that point every gram of grain you add means you will have less sugars at the end. 

Before you get to that point o you get into the 60s where it's painful. 

I have a spreadsheet which can quite reliably predict this stuff


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## RdeVjun (26/5/14)

Briefly, as per verysupple, Stux and others the BIAB sparge step that DOES improve efficiency is where the mash volume is quite limited, i.e. MaxiBIAB, particularly in the 19L stockpot.

The comparisons I have seen don't take this in to account, while some of the hysterical carry on we have witnessed about it completely overlooks the versatility and utility of the method, it puts an unnecessary straight jacket on what is really an adaptable technique.


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## Tex083 (26/5/14)

Not wanting to open a can of worms but I think with the effort of a dunk sparge your better off adding 2 teaspoons of calcium to correct mash pH.
Dont go overboard with water chem just add a bit and see what happens..... You wont go back, if its efficency points your after. Personally I have never measured mine. I hit my target OG, FG and adjust the vol. Usually dilute down to correct high OG's.


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## brando (26/5/14)

Tex083 said:


> Not wanting to open a can of worms but I think with the effort of a dunk sparge your better off adding 2 teaspoons of calcium to correct mash pH.
> Dont go overboard with water chem just add a bit and see what happens..... You wont go back, if its efficency points your after. Personally I have never measured mine. I hit my target OG, FG and adjust the vol. Usually dilute down to correct high OG's.


No need to assume here that anyone has incorrect mash pH... kinda off-topic mate.


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## verysupple (26/5/14)

Tex083 said:


> Not wanting to open a can of worms but I think with the effort of a dunk sparge your better off adding 2 teaspoons of calcium to correct mash pH.
> Dont go overboard with water chem just add a bit and see what happens..... You wont go back, if its efficency points your after. Personally I have never measured mine. I hit my target OG, FG and adjust the vol. Usually dilute down to correct high OG's.


It's getting a bit OT... But firstly, why would you tell someone to do something if you've never measured the effect it has? Secondly, you don't know what the OP's water is like, so you have no idea what effect "adding 2 teaspoons of calcium" might have. Thirdly, "adding 2 teaspoons of calcium" doesn't make much sense seeing as calcium isn't usually found unbound, and adding 2 teaspoons of different compounds will add different amounts of calcium. pH aside, calcium isn't going to make very much difference in your efficiency as the historical reasoning that it stabilises amylase was quite overstated. It'll help yeast flocculation among other things, but not mash efficiency.

Also, how out of whack was your mash pH if fixing it improved your efficiency more than a dunk sparge?


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## Markbeer (27/5/14)

I first starded sparging with biab when I did my first high gravity brew. I now do it all the time.

I believe alot of it has to do with the concentration of sugar vs water. ie add boiling water and it leaches out the sugar as they go from high concentration to low.

I will do 2 dunk sparges each for 10 minutes. I find it almost essential to do to be able to het decent efficuebcy in a 1075 plus brew.

for something like a mild I wouldn't bother.

this has stopped me from going to a 3v. I struggled to get decent efficuency for anything over 1055 until i started sparging.

Mark


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## brewbienewbie (27/5/14)

Ok so yesterday I did a repeat of last week's brew, but added a sparge step and my efficiency is back to normal. Gravity's seven points higher this time, I'm a happy man. I think I maybe could've got the same result if I mashed out properly, but for my system sparging with 6L or so of boiling water is much less effort.


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## Bribie G (27/5/14)

I'm doing an English 7% IPA for this years' comps. I'll do a single infusion mash plus mashout, then a dunky today and see how it goes. I've set my efficiency in Brewmate to 75% that's normally spot on for my regular 5% brews, lets see how it goes for a stronger brew. I'll reserve 10L of my original strike liquor for the purpose and use my immersion heater to take it to 78 degrees for the sparge.

Bribie puts chalk marks on neighbours' garage door to measure pissing height B)


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## Bribie G (27/5/14)

Great moments of BIAB.
Warning: do not attempt this with a Braumeister.







door go up, bag go up, door go down, bag go down. :lol: :lol: :lol: :lol:

edit: the gravity of those second runnings is 1.030 as opposed to about 1.060 (approx) for a similar 1.070 IPA done on "pure" BIAB so there's obviously less wasted sugaz now trapped in the grain ball. Not a heck of a lot I'd guess, but interested to see the final efficiency.


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## stux (27/5/14)

Dunk sparge can be almost perfectly modelled as a dilution.

So, the trapped sugars in the grain is just about equal to the real absorption of the grain at the mash gravity (the runnings)

Say there's 10L of absorption (real absorption, not apparent) at 1.060, then when you add another 10L of dunk sparge liquor you dilute, that to 1.030.

You then run off almost exactly the sparge liquor you added, ie 10L at 1.030...

And you're now left with 10L of 1.030 in your grain...

Another 10L sparge would get you another 10L of 1.015.

Calculating the real absorption is the trick, as it includes the volume of the extract.

With my triple batches it works out best if I can have 20L of sparge in a 50L pot. The limiting factor is the size of the pot as it must'nt overflow when you add the sodden grain!

PS: I find it best to dunk the bag, then open it and agitate with your masher (potato), to rewet all the grains. You're basically doing another mini biab. I let it soak while occasionally mashing again for 10 minutes... then hoist and drain off my second sky hook!


Attached pictures, first one is raising the bag and draining it, while bringing the wort up to boil temp.

Second is draining the dunk sparge.

I have a 2ring burner under the dunk sparge pot, and will bring that to the boil too, then pour it back into the main boil as I can as far as I can, volume allowing. I have an 11.5L/hr boil-off, so will get most of it in within 30-40 minutes I guess.

More Info on my 98/50L Maxi-BIAB setup
 Triple Batch Maxi-BIAB in 98L Kettle with 50L dunk sparge pot


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## Bribie G (27/5/14)

In my old place the urn(s) used to sit on a tool trolley and I would use one skyhook but move the trolley to position urn 1, urn 2 or the sparge bucket under the skyhook. Very impressive about bringing the dunk sparge pot up to the boil as well. I never thought about that but I have a perfectly good Kambrook single ring 2kw heater not earning its keep ... will try that next time I do a higher grav beer.


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## Bribie G (3/6/14)

I finally pitched the UK IPA just now and took a refrac reading of the wort as it went into the FV.. 73% efficiency according to BrewMate.

I'm pleased about that as it's a 6.2% ABV jobbie and I normally hit around 74% on my 5% brews.

edit IPA not APA


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