Author Topic: #5 Gravity Questions  (Read 1572 times)

Offline flbrewer

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#5 Gravity Questions
« on: March 24, 2015, 12:02:20 AM »
Good Evening! Knocked out brew #5 today and all went well...except dammit if I didn't forget the Whirfloc!

So my original gravities were off a bit from what Beersmith predicted and is now showing a 55% mash efficiency.

Est. Pre-Boil Gravity- 1.043 (Measured was 1.046)

Est. Original Gravity- 1.049 (Measured was 1.050)

Just to clarify, I took the pre-boil a minute or so after the boil began. I took the OG reading after everything was in the fermenter and I shook it up a bit. Also, not sure if it's important or not, I had to stir the mash for about 10 minutes to bring the temp down and I added 2 glasses of ice cubes (maybe that was enough to throw off some volumes).

Is this efficiency number WAY off?
« Last Edit: March 24, 2015, 12:06:47 AM by flbrewer »

Offline morticaixavier

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Re: #5 Gravity Questions
« Reply #1 on: March 24, 2015, 12:10:46 AM »
what was the recipe? or at least how much grain and what volumes?
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Offline flbrewer

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Re: #5 Gravity Questions
« Reply #2 on: March 24, 2015, 12:34:42 AM »
9.62 lbs. of grain. Mash thickness of 1.665, mash volume was 4 gallons, sparge volume was 3.37 gallons.

In case you need it, 2.75 gallons first runnings, 3.5 gallons from sparge.

Offline morticaixavier

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Re: #5 Gravity Questions
« Reply #3 on: March 24, 2015, 01:04:29 AM »
So, just looking at preboil gravity to take kettle losses out it works out like this (folks will correct my math where needed I'm sure)

9.62 lb of grain at 41 pppg = 394 and change

394/6.25 (your pre-boil volume) = 63 and change. This is your theoretical maximum possible extract. you say you measured 1.046 or 46 points

46/63 = .72 or 72% extraction efficiency. if your post boil gravity was 1.050 that means your post boil volume was 5.7 gallons. so your overall brewhouse efficiency is 394 points/volume in fermenter
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Offline flbrewer

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Re: #5 Gravity Questions
« Reply #4 on: March 24, 2015, 01:40:11 AM »
Jonathan, would you convert that to a percentage please? I'm assuming brewhouse is a better measurement than mash efficiency.

Offline morticaixavier

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Re: #5 Gravity Questions
« Reply #5 on: March 24, 2015, 02:19:36 AM »
brewhouse is sort of 'how much beer did I get for my 20 bucks worth of grain' so it's useful in that sense. extraction efficiency is important for troubleshooting. There is a third kind of efficiency and that is conversion efficiency which is a measure of how much of the available starch in the malt is converted into sugars in the tun. I'm assuming 100% here because modern malts are so hot.

you had 72% extraction efficiency. I can't tell you your brewhouse without knowing the volume into the fermenter. If the whole 5.7 gallons went in they you have 72% brewhouse, if only 5.5 gallons went in you have 5.5*50 = 275/394 = 69%, 5.25*50 = 262ish/394 = 66%
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Offline Alewyfe

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Re: #5 Gravity Questions
« Reply #6 on: March 24, 2015, 03:35:04 PM »
Jonathan,
I rely on Beersmith to do the math because mine is severly challenged, but I do like to understand the process and you've lost me. Where does the 41 pppg come from? Isn't that more like the points you'd get from extract?
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Offline reverseapachemaster

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Re: #5 Gravity Questions
« Reply #7 on: March 24, 2015, 03:49:42 PM »
If you boiled off quite a bit then your brewhouse efficiency should be around 55% as beersmith calculates.

I would not be too concerned about the variance from the estimated pre and post boil gravity readings. Remember that those are only estimates and the variance is slight. The wort volume going into the fermentor is an important metric that we do not know.

I don't know your exact recipe or setup in beersmith but it seems like you are not getting as much runnings out as you should and the mash efficiency isn't quite where it should be. If you had collected a greater volume of runnings then the pre-boil gravity would be far less which indicates a possible conversion issue as well as leaving behind runnings that you might need to collect. This is assuming your system is set up in beersmith accurately for your brewhouse.
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Offline morticaixavier

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Re: #5 Gravity Questions
« Reply #8 on: March 24, 2015, 04:11:29 PM »
Jonathan,
I rely on Beersmith to do the math because mine is severly challenged, but I do like to understand the process and you've lost me. Where does the 41 pppg come from? Isn't that more like the points you'd get from extract?

41could be a bit high. might be like 37. it's all an estimate anyway as every batch is different. with DME you get around 40-45 but you get it all.
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Offline denny

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Re: #5 Gravity Questions
« Reply #9 on: March 24, 2015, 04:13:42 PM »
9.62 lb of grain at 41 pppg = 394 and change

That should be more like 36 ppg, shouldn't it?
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Offline morticaixavier

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Re: #5 Gravity Questions
« Reply #10 on: March 24, 2015, 04:16:19 PM »
9.62 lb of grain at 41 pppg = 394 and change

That should be more like 36 ppg, shouldn't it?

regardless he got much better than 55% efficiency. not sure where I came up with 41. my brain is like a really messy closet lately. Full of useful stuff but not always easy to get to.
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Re: #5 Gravity Questions
« Reply #11 on: March 24, 2015, 04:32:00 PM »
9.62 lbs. of grain. Mash thickness of 1.665, mash volume was 4 gallons, sparge volume was 3.37 gallons.

In case you need it, 2.75 gallons first runnings, 3.5 gallons from sparge.

You're losing ~5% (0.15 gal) to either dead space or incomplete lautering of the first runoff. Figuring out a way to get all that wort out would be a good start if improving efficiency is the goal.

Taking a step back, though, your measured gravities are *really* close to what you expected. So regardless of what your mash efficiency actually is (somewhere around 80%), it's very nearly what the recipe was formulated for.
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Offline Alewyfe

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Re: #5 Gravity Questions
« Reply #12 on: March 24, 2015, 04:38:43 PM »
9.62 lb of grain at 41 pppg = 394 and change

That should be more like 36 ppg, shouldn't it?

regardless he got much better than 55% efficiency. not sure where I came up with 41. my brain is like a really messy closet lately. Full of useful stuff but not always easy to get to.
I'm stealing that line....but mine is always like that, not just lately.

If Beersmith is not set up correctly you can get some weird numbers. It's important for brewers to understand how to compute gravity points so they can double check themselves and you can't just plug an arbitrary number. You were teaching the OP something important Mort. Just didn't want him thinking 41 was the magic number as it varies by grain bill.
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Offline morticaixavier

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Re: #5 Gravity Questions
« Reply #13 on: March 24, 2015, 04:58:22 PM »
[...] my brain is like a really messy closet lately. Full of useful stuff but not always easy to get to.
I'm stealing that line....but mine is always like that, not just lately.

If Beersmith is not set up correctly you can get some weird numbers. It's important for brewers to understand how to compute gravity points so they can double check themselves and you can't just plug an arbitrary number. You were teaching the OP something important Mort. Just didn't want him thinking 41 was the magic number as it varies by grain bill.
[/quote]

help yourself ;)

i should have mentioned the variability in my initial response but didn't want to get too complex.
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Re: #5 Gravity Questions
« Reply #14 on: March 24, 2015, 06:26:43 PM »
As an engineer, I much prefer understanding the equations, doing them by hand and then Inputting them into excel so I have everything under control on my own.

This translates to brewing very easily.