Author Topic: Missed Target Gravity, want to supplement  (Read 1020 times)

Offline singindave

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Missed Target Gravity, want to supplement
« on: August 07, 2010, 06:16:07 AM »
I Brewed a Rye IPA last night and my target gravity (1.060) (my typical 70% brew-house efficiency) was well missed (1.044), my IBUs will be a too high if I leave it as is (1.044 OG for ~65 IBUs is lacking on the malt).  Fermentation is just about to start, and I was thinking of adding 1 gal of high gravity unhopped wort (3# of DME, boiling that in 1gal for 30min or so), this would (in theory) give me ~6gal of 1.060 OG, 55 IBUs or so.  Has anyone ever done this, think it is a good/ bad idea?  If you think it would work, when should I add the new wort, High Kreausen, or secondary, somewhere between?
Any thoughts would be greatly appreciated. 
6# 2-Row
4# Rye Malt
1# Vienna
1# Munich
0.5# Honey malt
0.5# rice hulls
5Gal Round cooler, false bottom.
4Gal 160F water -> ~150F for 50min, 1gal 210F water to ~160 for 15min, recirculate ~2gal, continuous sparge to ~6.5 gal with ~175F water, collection time ~25min for 26 quarts (too fast? too slow? Why not do batch sparging?)
This is the 5th normal (OG between 40 and 70) batch I have done with the mash tun, and before my efficiency was 70, 71, 70, 75%
Any help on what happened to my efficiency, when removing the grain bed to dry some, pressing out water resulted in nice thick sweet syrup, any thoughts on how best to add that to my brew kettle rather than onto my hand?

Offline denny

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Re: Missed Target Gravity, want to supplement
« Reply #1 on: August 07, 2010, 07:54:47 AM »
Your plan should work fine.  I'd get the DME/water mixture in there ASAP.
Life begins at 60.....1.060, that is!

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Offline abraxas

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Re: Missed Target Gravity, want to supplement
« Reply #2 on: August 07, 2010, 08:05:01 AM »
I did this just the other day...thought I missed my mash temp due to a thermocouple acting funny, over-adjusted, adjusted back and lost some efficiency due to the lower sparge volume. 

Not enough DME on hand so I just boiled up some in a gallon of water the next day and added to the fermenting beer.  So far, so good.

Just take into consideration that 1 gallon + 3 lbs DME will be more than a gallon, if you are trying to be precise about it.

Offline tschmidlin

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Re: Missed Target Gravity, want to supplement
« Reply #3 on: August 07, 2010, 01:12:52 PM »
Yeah, add it before high krausen in case you are introducing any more O2 to the batch, and make sure you have enough room for how much you plan to add.

As for missing your gravity, if you followed your normal procedures I'd look at your crush for starters.  I just did a batch and missed low by a few points, and looking at the grain in the tun there were some uncrushed grains mixed in.  My LHBS just got a nice 3-roller Monster Mill, but they've been fiddling with it and I think they have the gap too loose.  I should have checked when I milled the grains.

You can also slow your sparge or go with hotter water - I always sparge with 180-190 degree water because I get a pretty sizeable temperature drop from my sparge arm and the mash never gets up above 165 unless I use near-boiling water to sparge.  It all depends on your system.
Tom Schmidlin

Offline timmyr

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Re: Missed Target Gravity, want to supplement
« Reply #4 on: August 08, 2010, 06:22:07 AM »
Your plan should work fine.  I'd get the DME/water mixture in there ASAP.

+1, I'd just adjust by total Gravity Units which account for volume and shoot a little low to avoid overcompensation and inadvertently diluting the IBUs too much...and take good notes so if its AMAZING, then you can reproduce.
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Offline gordonstrong

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Re: Missed Target Gravity, want to supplement
« Reply #5 on: August 08, 2010, 11:04:09 AM »
Yes, your approach will work.  It's best to measure your gravity before the boil so you can decide if you need to supplement the fermentables while you're still on the hot side of brewing.  Measure your starting volume, measure your gravity, figure out how many points of fermentables are in the kettle.  Divide by your target volume to get your target gravity.  If it's not what you want, either change the points in the kettle, or change the volume at the end.  Much better to do it here than to have to dink around with it once it's in the fermenter.  Not that it helps you with this batch...

Did you hit your volumes?  That often is what messes up target gravity.

Do you stir your mash?  That can make a big difference in efficiency.

For sparging, try cutting channels in the grain bed before you start.  Use a long, thin spatula and cut a checkerboard pattern in the grain, maybe 1-2" square.  Sounds lame but it actually does help.  Trick from Sierra Nevada.
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Offline jalynn2

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Re: Missed Target Gravity, want to supplement
« Reply #6 on: August 09, 2010, 04:51:47 PM »
That's interesting Gordon. I always heard that a channel through the grain bed was bad because it gave the sparge water an easy path through (or so the theory went). I guess the many channels make up for that? How deep do you cut? Do you cut it before or after vorlauf? I usually get around 75%, but I'll give it a try on the next batch. Thanks for the tip.

Offline gordonstrong

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Re: Missed Target Gravity, want to supplement
« Reply #7 on: August 09, 2010, 06:50:21 PM »
It's described in the Beer Camp article I wrote in Zymurgy last fall.  You don't cut all the way through the grain bed, just most of the way. I forget what the article said, probably something like an inch or two above the bottom.

When the literature talks about channeling being bad, they mean one channel through the whole bed.  Yes, that's bad, for the reason you described.  But when you have as many I'm talking about, the effect is different. It's like water draining through a mesh screen rather than through a single drain. You have multiple paths, all through the grain bed, so you're encouraging water to go through the entire grain mass. The channels are very thin (use a spatula, not a stick) so the water doesn't just fall through.

Do this before the vorlauf, since the idea of a vorlauf is to set your bed so you can runoff clear. Cutting into the mash messes up the bed a bit, so you want to vorlauf afterwards. Basically, you want to runoff directly from the vorlauf without touching the mash again, once it's clear.

I use a long, thin offset spatula from the kitchen.  It was probably from Williams-Sonoma if you want to google for it, but a thin piece of steel would work just fine. It doesn't have to be totally rigid, just be able to cut through when you slice with it.
Gordon Strong • Beavercreek, Ohio • AHA Member since 1997 • Twitter: GordonStrong

Offline susanr

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Re: Missed Target Gravity, want to supplement
« Reply #8 on: August 10, 2010, 11:27:57 AM »

Do this before the vorlauf, since the idea of a vorlauf is to set your bed so you can runoff clear. Cutting into the mash messes up the bed a bit, so you want to vorlauf afterwards. Basically, you want to runoff directly from the vorlauf without touching the mash again, once it's clear.

I use a long, thin offset spatula from the kitchen.  It was probably from Williams-Sonoma if you want to google for it, but a thin piece of steel would work just fine. It doesn't have to be totally rigid, just be able to cut through when you slice with it.

I learned this trick when I first started homebrewing back in '96.  You can cut the bed with any thin object - I use the end of my stir spoon.  Cutting the bed actually keeps the sparge from channeling.  I usually cut 2-3 times during the sparge - just don't cut more than an inch or so into the grain bed and you won't have any worries about messing up your clear runnoff.
Cheers,
Susan

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Offline dzlater

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Re: Missed Target Gravity, want to supplement
« Reply #9 on: August 10, 2010, 12:39:30 PM »
     Last time I brewed I got way better efficiancy then I was planning on, The preboil gravity was actually higher then the targeted OG.
     I wanted to increase my hop additions to maintain the BU/GU ratio. But I couldn't quite figure out the math. I wound up just estimating. Is there an easy way to  to this?

Offline gordonstrong

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Re: Missed Target Gravity, want to supplement
« Reply #10 on: August 10, 2010, 08:04:51 PM »
Brewing software helps.  I started brewing with my iphone close by, and I have both Beer Alchemy and BrewPal loaded.  Beer Alchemy has more features, but BrewPal is fairly quick with calculations.  I find myself using it most for the quick things like this.

But I have an estimating way that is probably close enough.  I'm assuming that you know what BU:GU that you want and that you know the GU, so you also know the new BU, right?  So you're asking how do you figure out how many hops you need to get that BU on the fly?

I once calculated that a 60 minute addition of whole hops gave you about 3.5 IBUs for every AAU added.  So if you know how many IBUs you need, you then figure out how many AAUs you add.  Take a look at the AA on your hops and then you can tell how many ounces to add.

I didn't run the math for other types of additions, but you can find the formula and run the numbers for what you commonly use.  Figure out the number that matches how you brew, and then remember that factor in case you have to do quick adjustments.

This is an approximation; it's not exact, and it doesn't work for every case.  But it is easy to remember and works just fine if you know the constraints.
Gordon Strong • Beavercreek, Ohio • AHA Member since 1997 • Twitter: GordonStrong

Offline dzlater

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Re: Missed Target Gravity, want to supplement
« Reply #11 on: August 11, 2010, 08:02:25 AM »
I think I get it.

If I need to add 11.4 IBUs to keep the BU/GU ratio the same
1 oz of 5% would give me 17.5 ibus ----  ( 3.5x5 )=17.5
11.4/15.5= 0.65
I would have to add 0.65 oz of a 5% AA hop?

I ran into this problem on my last brew and unfortunetly
I was having some issues with my brewing software.

Thanks

Offline denny

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Re: Missed Target Gravity, want to supplement
« Reply #12 on: August 11, 2010, 08:37:11 AM »
I once calculated that a 60 minute addition of whole hops gave you about 3.5 IBUs for every AAU added.  So if you know how many IBUs you need, you then figure out how many AAUs you add.  Take a look at the AA on your hops and then you can tell how many ounces to add.

Way cool formula, Gordon.  In the BJCP study group I've been teaching, I've been trying to teach people how to figure recipes on the fly.  I'd told them that on average, a lb. of grain in a 5 gal. batch will yield 5 GU at 75% efficiency.  We'll use your hop formula, now, too.  Thanks!
Life begins at 60.....1.060, that is!

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Offline gordonstrong

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Re: Missed Target Gravity, want to supplement
« Reply #13 on: August 11, 2010, 11:09:30 AM »
Yeah, I originally developed that for a BJCP study class. FYI, I figured 10 lbs of grain gave you 1.054 so we're close. Good enough for the recipe question on the exam.
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