Fly Sparging With Low OG beers

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Beerandgranite

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I have recently started fly sparing with very good results in mash efficiency (72% to 88% allegedly). I brewed a Bock and Helles bock both with an OG over 1060 with no issues.
However, this weekend I brewed a german pils (og of 1048), and noticed that really early into the fly sparge that the runnings from the mash tun were incredibly clear. I did not account for this and with a bit of research in the moment, I quickly learned that you don't want your running to fall below 1010 due to tannin extraction. I stopped the fly sprage and checked the runnings, and sure enough they were at 1011, and was 1.25 gallons short of my pre boil volume.
I havent been able to wrap my head around how to correct this. a few ideas:
  • the error was in my recipe design. should I over build the grain bill and dilute in the kettle to reach target OG?
  • the error was in my mash and sparge volumes (1.5qt/lb mash thickness). Would a thicker mash be a solution to this?
  • Fly sparging may not be appropriate for low OG beers ?
  • the problem is possibly overstated and cant be avoided
How do you fly sparge when brewing low OG beers while preventing runnings from falling below 1010 and still hitting your target pre boil volume?
 

VikeMan

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Acidify your sparge water (to roughly the same pH as the mash) and you won't have to worry about extracting excess tannins.
 
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Beerandgranite

Beerandgranite

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Acidify your sparge water (to roughly the same pH as the mash) and you won't have to worry about extracting excess tannins.
I see, tannis are only extracted when running fall below and 1010 and the ph is high? i am also using RO water (assuming ph of 7), any recommendation on the best way to acidify?
 

VikeMan

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I see, tannis are only extracted when running fall below and 1010 and the ph is high? i am also using RO water (assuming ph of 7), any recommendation on the best way to acidify?

It's not really about the gravity per se. And there is no magic cutoff that eliminates tannin extraction. Tannins are a normal product of every mash. Too much tannins is where astringency becomes a problem.

The hotter the sparge, the more tannins are extracted. The higher the pH, the more tannins are extracted. The lowering of the gravity as the sparge progresses is the result of the wort being diluted by the (higher pH) water, thus also raising the pH of the runnings.

All that said, if you sparge with good RO water, you don't need to worry about it. It has almost no buffering capacity, so it won't shift the pH of your runnings noticeably.
 
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Beerandgranite

Beerandgranite

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It's not really about the gravity per se. And there is no magic cutoff that eliminates tannin extraction. Tannins are a normal product of every mash. Too much tannins is where astringency becomes a problem.

The hotter the sparge, the more tannins are extracted. The higher the pH, the more tannins are extracted. The lowering of the gravity as the sparge progresses is the result of the wort being diluted by the (higher pH) water, thus also raising the pH of the runnings.

All that said, if you sparge with good RO water, you don't need to worry about it. It has almost no buffering capacity, so it won't shift the pH of your runnings noticeably.
I see, while i am using RO water, i put the entire volume in the HLT (strike and sparge) and add mineral additions. does this increase the RO water's buffering capacity when it comes time to sparge? it would seem I need to deepen my understanding of subject.
 

VikeMan

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I see, while i am using RO water, i put the entire volume in the HLT (strike and sparge) and add mineral additions. does this increase the RO water's buffering capacity when it comes time to sparge? it would seem I need to deepen my understanding of subject.

It depends on what minerals you added. For example, CaCl2, CaSO4, MgCl2, MgSO4, and NaCl won't increase the buffering capacity. But CaCO3, NaHCO3, and Ca(OH)2 will increase the buffering capacity.
 

TheMadKing

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Decrease your mash thicknesses. It will result in less sparge water needed.

Alternatively you could sparge faster and reduce your lauter efficiency intentionally.

I fully support everything Vikeman said and I never experienced astringency issues doing as he advised. But even with properly acidified sparge water I had a reocurring issue with haze formation in my low OG beers. I eventually concluded it was due to over sparging. I have decreased my mash thickness to 2 or even 2.5 qt/lb resulting in much less sparge water which seems to have solved my issue.

This is purely anecdotal and based on observations, I haven't researched the chemistry to back it up though.
 

Red over White

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Most of my brews are 1.038-1.046 and I kinda split the difference on the great advice given above. With acidified sparge water, I shoot for low 70's ending kettle efficiency and it almost doesn't fail to hit the mark on volume and gravity. Slow sparge for 30 minutes and then a fast sparge at the end. I use less overall water than most 3V systems do, but it just works.
 

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TheMadKing is right on (as is VikeMan). I've found that keeping my sparge water at half or, ideally, less than half of my entire water budget helps to avoid problems with lower gravity beers. Utilizing a looser mash is a great way to do this. It also creates a larger thermal mass, which helps with heat retention and there's also a school of thought (that I subscribe to) that argues that looser mashes make for more fermentable worts, all things being equal. This used to be a topic of lively debate, not sure if it still is.

Since you're brewing German stuff, use this as an opportunity to do some infusion step mashing. I'm a big fan of the Hochkurz mash, it's a simple step mash program that is easy to perform via infusions on average strength beers and it does a great job at gobbling up your sparge budget.

Lastly, there's no rule that says you have to sparge. Assuming your tun has the necessary volume, I've found that no-sparge mashes produce excellent results for truly low gravity stuff, like Ordinary Bitters, Milds, etc.
 

Red over White

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I just ran my numbers on the back of a napkin and I use on average 36% of my total liquor in the sparge. Which works good on my working man strength beers. I typically average ½ gallon left in the mashtun as I ramp to boil.
 

MicroMickey

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Alternatively you could sparge faster and reduce your lauter efficiency intentionally.
I hate to say it but it's like having a nearly empty tank and speeding to the gas station before you run out.
VikeMan is right. Pay attention to the pH of the sparge water. Tannin extraction mainly occurs when the pH goes above 5.9 - 6.0. No matter what your mash pH is, as the buffers in the mash are rinsed out by the sparge water, the pH will rise.
 

TheMadKing

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I hate to say it but it's like having a nearly empty tank and speeding to the gas station before you run out.
VikeMan is right. Pay attention to the pH of the sparge water. Tannin extraction mainly occurs when the pH goes above 5.9 - 6.0. No matter what your mash pH is, as the buffers in the mash are rinsed out by the sparge water, the pH will rise.
I'm not sure I follow your analogy here... but I did agree that vikeman was right as well. No argument that the pH of sparge water is important, and I never said that the speed of sparging affects the pH or tannin extraction (if that's what you're saying?.. I might be misunderstanding)

Increasing lauter speed will increase channeling and decrease the amount of time that sparge water is in contact with the grain. That means the osmosis of the sugar migrating into the sparge water has less time to work which all makes for a less efficient sparge. A less efficient sparge will keep your end of runnings gravity higher than a long slow fly sparge.

I think the haze I was seeing was either a protein issue or other polyphonic compounds from the grain, but as I said I never experienced astringency because I was controlling my sparge pH
 

TheMadKing

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how fast are you sparging? maybe slow it down a lot? that way the sparge water has more time to 'mingle'?
Slowing down the sparge (so that it takes between 40-60 minutes) is likely to make it more efficient. Beyond that point it will have no real effect.

That means for a given volume of sparge water (say 3 gallons for the sake of example), your runnings gravity will reach 1.010 after only 2 gallons have gone through.

If you speed up the sparge (say 15-20 minutes) it will tend to make it less efficient and result in getting through the full 3 gallons of sparge water before your runnings gravity drops to 1.010
 

bracconiere

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Slowing down the sparge (so that it takes between 40-60 minutes) is likely to make it more efficient. Beyond that point it will have no real effect.

That means for a given volume of sparge water (say 3 gallons for the sake of example), your runnings gravity will reach 1.010 after only 2 gallons have gone through.

If you speed up the sparge (say 15-20 minutes) it will tend to make it less efficient and result in getting through the full 3 gallons of sparge water before your runnings gravity drops to 1.010



i was thinking along the lines of the 2" of cap water on top 'slowly' moving down would pick up more gravity from the grains? if all you're doing is spraying off the surface of the grain, and not really wringing them out..?
 

TheMadKing

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i was thinking along the lines of the 2" of cap water on top 'slowly' moving down would pick up more gravity from the grains? if all you're doing is spraying off the surface of the grain, and not really wringing them out..?

you're correct that's exactly what would happen. So by the time you get to that last gallon of totally clear water flowing through your grains and there's no sugar left to grab, it *seems reasonable* to conclude that it's picking up something polyphenolic from all that plant matter, even if it's not tannins.
 
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