Missed starting gravity

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Brandon1987

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Hi,
i brewed a belgian witbier today and the estimated pre boil gravity was 1.041 and the actual pre boil gravity was 1.062. way too high.
now the estimated post boil gravity was 1.046 and the actual post boil gravity was 1.038. way too low.
i mashed for 60 minutes recirculating at 148 degrees f. and my hydrometer is calibrated correctly i checked. and i cooled the sample down correctly. i have never had this issue before. this is supposed to be a 5% ABV finished beer but i am now at best looking at 3.8%. my brewhouse efficiency is 75%, or so i thought. what have i done wrong. thanks for the help. 5 gallon batch btw.
 

downzero

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Your specs and measurements are both wrong. Pre-boil gravity can't be higher than post-boil if you don't add water to the post boil. Boiling off water increases specific gravity. Who cares about your pre-boil gravity anyway? It sounds like you missed your target OG, either from too much water or low efficiency. Your alcohol content may be lower on the other side of the fermentation, but you'll have to measure it to be sure.

None of this is anything to worry about.
 

doug293cz

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It is impossible for the post-boil SG (OG) to be lower than the pre-boil SG. You lose water during boil but no sugar, so the sugar concentration has to be higher (i.e. higher SG) after boil.

Need more details on your process in order to guess why your measurements are borked. Sparge vs. no-sparge, batch or fly, grain bill, volumes (strike, sparge, pre-boil, post-boil), how SG measured and at what temp, etc.

Brew on :mug:
 
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Brandon1987

Brandon1987

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It is impossible for the post-boil SG (OG) to be lower than the pre-boil SG. You lose water during boil but no sugar, so the sugar concentration has to be higher (i.e. higher SG) after boil.

Need more details on your process in order to guess why your measurements are borked. Sparge vs. no-sparge, batch or fly, grain bill, volumes (strike, sparge, pre-boil, post-boil), how SG measured and at what temp, etc.

Brew on :mug:
Thanks for the feedback. I batch sparged.
Grain bill is 4 Pounds Belgian Pils Malt
4 pounds red wheat malt
8 ounces flakes oats
Mash water volume 3.16 gallons
Sparge water volume 4.09 gallons
SG measured with hydrometer at 68 F
I haven’t had any issues hitting my numbers in a long time. I recirculated the mash for 1 hour at 148F.
 

tochsner

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Hard to say exactly what you did wrong but it has to do with the measuring. It's not possible that your post boil gravity is lower than you pre-boil. It can't go down when you boil of some water. I would recheck the gravity of the wort in the fermenter and use that as your OG.
 

FunkedOut

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Do you sparge?
I could never get a pre/post boil set of readings to match calculations, so I gave up on those pre-boil readings.
I just calculate back from the post-boil readings to get my mash effeciency.
It’s damn near impossible for me to get a thorough mix pre-boil after the sparge.

I found a few points preventing evaporation.
In a small gravity reading sample, a small amount of evaporation can really affect your reading.
I would sample with a syringe to eliminate any evaporation.

In the end, I was still a couple points too high on pre-boil.
I guess some stuff falls out of suspension in the boil.
At the end of the day, as long as your boil-off volume is consistent, the only gravity that matters is the post-boil.
 
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Brandon1987

Brandon1987

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Hi all. So it has occurred to me that I originally got my pre boil gravity reading before sparging when I should have done it after sparging before boiling. That is why my pre boil reading was 1.062 instead of the estimated 1.041. Now my measured BH efficiency is 75%. But I didn’t hit my gravity readings since the estimated post boil was 1.046 and I got a reading of 1.038. The grain bill was only 8.5 pounds for this Belgian witbier. I didn’t time my batch sparge but I think I sparged too quickly or something. I batch sparged with 4 gallons 1 gallon at a time. Maybe took 10 -15 minutes. That seems too quick to me. I usually brew 5 gallon batches with around 11-12 pounds of grain and of course sparging takes longer with more grain. How could I improve my sparging? Or is that even why my efficiency was low this batch? Thanks for the help.
 

day_trippr

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Unlike fly sparging, the only constraint in batch sparging is the physical limit of your lautering. Also, unlike fly sparging, there's no "channeling" to worry about.

So there's zero reason to go slow. You've already stirred the mash plus sparge liquor so whatever the latter is going to pull out of the former is done, so no reason to throttle your runoff...

Cheers!
 

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Glad you figured out the measurement issue.

You're only 8 points off your estimated OG - not optimal but not horrible, either.

One of the first places to look to explain a poorer than expected brewhouse efficiency is the crush of your grain. Do you crush your own malt or did you buy it crushed?
 

kh54s10

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Yes, with batch sparging, pour the water in and stir it up very well, vorlauf to set the grain bed then crack the valve a little. Once it is going pretty well open the valve all the way. You cannot batch sparge too fast. There is also no reason to break up your sparge into four one gallon steps. I do two steps but that is only to get my boil volume very close, leaving very little water/wort in the tun.

I suspect the problem with your OG is due to either bad measurements or poor grain crush.
 
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Brandon1987

Brandon1987

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Glad you figured out the measurement issue.

You're only 8 points off your estimated OG - not optimal but not horrible, either.

One of the first places to look to explain a poorer than expected brewhouse efficiency is the crush of your grain. Do you crush your own malt or did you buy it crushed?
I crushed the grain at the homebrew supply store. I’d guess that they’d have the mill in spec.
 

kh54s10

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I crushed the grain at the homebrew supply store. I’d guess that they’d have the mill in spec.
An LHBS will mill to a point where almost no one will get a stuck sparge.. That is way too coarse for most BIAB, and with my mash tun I can go almost as fine as with BIAB. I still suspect too coarse a grind or measurement error.
 

RM-MN

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I crushed the grain at the homebrew supply store. I’d guess that they’d have the mill in spec.
The LHBS has no incentive to crush the grain fine and every incentive to crush it a little coarse. If they crush too fine they will get yelled at by their customers who deal with a stuck mash and/or sparge. Leaving the mill gap a little wide avoids that and it can be compensated by adding a little more grain to the recipe and they just happen to sell grain. Also, crushing fine puts more wear on the mill so it needs more maintenance. It's better for you to buy your own mill and buy grain in bulk if you have the storage room for it. Bulk grains are cheaper and with your own mill you can mill the grain finer so you get better efficiency, thus needing less grain per batch.
 
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Brandon1987

Brandon1987

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The LHBS has no incentive to crush the grain fine and every incentive to crush it a little coarse. If they crush too fine they will get yelled at by their customers who deal with a stuck mash and/or sparge. Leaving the mill gap a little wide avoids that and it can be compensated by adding a little more grain to the recipe and they just happen to sell grain. Also, crushing fine puts more wear on the mill so it needs more maintenance. It's better for you to buy your own mill and buy grain in bulk if you have the storage room for it. Bulk grains are cheaper and with your own mill you can mill the grain finer so you get better efficiency, thus needing less grain per batch.
This makes so much sense. Thanks a lot for the information. I’m always looking to improve my brewhouse efficiency.
 

RM-MN

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What kind of mil would you recommend and where could I find one ?
There are too many variables for me to make such a recommendation. If you are using a conventional mash tun and intend to keep doing so, then a roller mill of some kind will be fine. If you want to make some changes, BIAB (in the boiling kettle or in the mash tun cooler) can handle a much finer milling which can then bring your mash efficiency way up. This is because a conventional mash tun depends on the husks of the grain to provide the filter material for draining and if the husks get torn up they won't function that way. Adding a fine mesh bag allows much finer milling as you depend on the bag itself to form the filter and the quality of the husks make no difference. If you use the bag in a cooler, you may need to lift it some so the cooler will drain. I do BIAB in the boil kettle and use a cheap Corona mill set a tight as I can get it. You can find them online for around $20 to $25 and up.
 
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Brandon1987

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There are too many variables for me to make such a recommendation. If you are using a conventional mash tun and intend to keep doing so, then a roller mill of some kind will be fine. If you want to make some changes, BIAB (in the boiling kettle or in the mash tun cooler) can handle a much finer milling which can then bring your mash efficiency way up. This is because a conventional mash tun depends on the husks of the grain to provide the filter material for draining and if the husks get torn up they won't function that way. Adding a fine mesh bag allows much finer milling as you depend on the bag itself to form the filter and the quality of the husks make no difference. If you use the bag in a cooler, you may need to lift it some so the cooler will drain. I do BIAB in the boil kettle and use a cheap Corona mill set a tight as I can get it. You can find them online for around $20 to $25 and up.
I use the Brewer’s Edge mash & boil. Wouldn’t that be considered a BIAB or eBIAB?
 

RM-MN

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I use the Brewer’s Edge mash & boil. Wouldn’t that be considered a BIAB or eBIAB?
Yes it would be an eBIAB but there are 2 models, one without a pump and one with. The one with the pump requires a coarser crush or it will spill over because the fine particles will clog the mesh of the bag during the recirculating. Without the pump you can mill the grain to near flour and it will be fine.
 

Alex4mula

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I use the Brewer’s Edge mash & boil. Wouldn’t that be considered a BIAB or eBIAB?
I also have the Mash & Boil without pump. I recirculate manually through the mash. No biggie. The only improvement I mentioned above was with the Cereal Killer from Adventures In Homebrewing. I started crushing at 0.048. Today I brewed again and hit all the numbers. Loving the little thing :)
 
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Brandon1987

Brandon1987

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Yes it would be an eBIAB but there are 2 models, one without a pump and one with. The one with the pump requires a coarser crush or it will spill over because the fine particles will clog the mesh of the bag during the recirculating. Without the pump you can mill the grain to near flour and it will be fine.
Ok. I have the one without the pump but I bought a chugger pump and I use it when I mash. I just regulate the flow as best I can. Does a good job of keeping even temperature throughout the mash.
 

Alex4mula

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Ok. I have the one without the pump but I bought a chugger pump and I use it when I mash. I just regulate the flow as best I can. Does a good job of keeping even temperature throughout the mash.
I just bought a pump and will be setting it up for the next brew.
 
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