how do you take pre-boil gravity readings?

Yakima 728
Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
lpdb185

lpdb185

Well-Known Member
Joined
Sep 29, 2009
Messages
426
Reaction score
0
Location
Jackson
i'm trying to think of everything i can for my first AG attempt. as i understand it, i need to get gravity readings from each of the 3 runnings from my mash tun (i plan on using Bobby_M's double batch sparge method) and one overall pre-boil sample. what are some of your methods of doing this? do you pull a sample and immediately take a reading with hydrometer (assuming it will not shatter)? or do you draw a sample, let it cool, then take a reading? i'm sure it doesn't matter for the sake of calculation, but i'm really wondering how you fine folks do this in order to be most efficient with your brewing time.

i've heard of people using temperature corrections for gravity readings, so i'm assuming i am supposed to take the gravity reading while the wort is still at mash temp. if that's correct, where can i find a temp correction guide/tutorial/spreadsheet? or, is this something that Beersmith will do for me?


thanks for your help
 
I will pull a sample after I vorlauf each time, & then stick it in the freezer to cool it quickly. I won't take a gravity reading until it's below 100, then I will use temp corrections. There is a table in How to Brew that gives you corrections, page 264 & 265 of the hardcopy. I don't use brewing software, so I'm not sure about beersmith.
 
You will have to get all of your runnings into the kettle and mix WELL before you attempt a preboil reading. I draw some off into my measurement cylinder and put it in the freezer to cool it down to at least 80 F then take a reading and correct for temp.

Of course if you had a refractometer you wouldn't have to worry about the cooling.
 
float a small mixing bowl in a pot or bowl filled with ice water. I used a pie plate in a big mixing bowl filled with ice. I filled my (plastic) hydrometer flask to the desired level, dumped it into the dry(!) pie tin, swirled it with a spoon for 15-20 seconds: 63F.
 
lpdb185 said:
i'm trying to think of everything i can for my first AG attempt. as i understand it, i need to get gravity readings from each of the 3 runnings from my mash tun (i plan on using Bobby_M's double batch sparge method) and one overall pre-boil sample. what are some of your methods of doing this? do you pull a sample and immediately take a reading with hydrometer (assuming it will not shatter)? or do you draw a sample, let it cool, then take a reading? i'm sure it doesn't matter for the sake of calculation, but i'm really wondering how you fine folks do this in order to be most efficient with your brewing time.

i've heard of people using temperature corrections for gravity readings, so i'm assuming i am supposed to take the gravity reading while the wort is still at mash temp. if that's correct, where can i find a temp correction guide/tutorial/spreadsheet? or, is this something that Beersmith will do for me?


thanks for your help
Click to expand...

I batch sparge and used to take a sample from the 1st, 2nd, and 3rd runnings (I boil 13.5 gal for a 11 gal post boil batch) but I never used the data collected for any purpose. Now I just take a sample pre and post boil. Pre boil sample comes out of the kettle at sparge temperature and I just let it cool to room temperature. Post boil is taken after cooling and whirlpool before draining to fermenter. The actual hydrometer measure takes place last thing when all clean up is done which is usually 4 -5 hours after pre boil sample is taken. All I calculate is brew house efficiency and a baseline to measure attenuation after fermenation is done.

I don't bother pulling samples to determine when the beer is done if my blowoff tube displays "normal" rate of CO2 discharge during active phase. I let it stay in fermenter for 2 weeks, pull a sample to measure attenuation and keg it up.
 
Yes, beersmith does have a hydrometer correction tool that lets you put in your temp and measured gravity and it converts it.

I usually draw off the wort, stick my thermometer in to get a temp, take the gravity reading, then take the temp again. I average out the temps to use as the temp the gravity was read at and then plug that into beersmith.

I haven't had a problem with cracking the hydrometer. As long as you don't move it from really warm wort (150 degrees) and then rinse it off with 40 degree tap water you should be fine. I usually rinse it off with hot water from my tap and its never an issue.
 
I would just take one reading after sparge is finished. Cool it to 60 and that will be the pre-boil. You can get your efficiency from this if you have carefully measured your volumes.
 
wow, thanks for all the input. i thought i had read that you needed samples from each of the runnings, but never heard exactly why they needed to be split up like that. perhaps i'll just get the overall preboil gravity, like some of you say, and keep it simple. thanks for the link manticle.

if i decide to get a hydrometer, do i need to look for anything particular? are they all pretty much equal, or do i need to look for something specific? i ask because i breifly looked on the web and they are anywhere from $30 to $80.

thanks -
 
do you know what your evaporation rate is? Also getting a reading from each runnings is so you don't over sparge
 
kryolla said:
do you know what your evaporation rate is? Also getting a reading from each runnings is so you don't over sparge
Click to expand...

no i don't. this will be my first time brewing with my keggle. it's probably a little much for a 5g batch, but i'm on a budget and it was cheap (free). i thought about giving all my equipment a test run with boiling water, but i'm not sure if that would boiloff the same as higher gravity wort (correect me if i'm wrong).

for beersmith (which i really haven't got figured out yet), i just left it at 9% because that it what the 15g pot had preset.
 
I take 3 readings on brew day.

1) First Wort gravity - just take a sample during the first runnings.
2) Pre Boil - stir the kettle well after getting all the runnings in.
3) Original Gravity - just take a sample while draining into the fermenter.

I collect the samples in small glasses and set them on the counter. After my brew day is done they're all at room temperature and I can take hydrometer readings with minimal adjustments.
 
It seems that taking readings of each running separately can help target where efficiency problems are happening.
 
lpdb185 said:
no i don't. this will be my first time brewing with my keggle. it's probably a little much for a 5g batch, but i'm on a budget and it was cheap (free). i thought about giving all my equipment a test run with boiling water, but i'm not sure if that would boiloff the same as higher gravity wort (correect me if i'm wrong).

for beersmith (which i really haven't got figured out yet), i just left it at 9% because that it what the 15g pot had preset.
Click to expand...

A test run will get you in the ball park. If you miss your pre-boil gravity do plan on adding some extract or boiling longer, if adding extract do you know how much, how do plan on correcting it?
 
kryolla said:
A test run will get you in the ball park. If you miss your pre-boil gravity do plan on adding some extract or boiling longer, if adding extract do you know how much, how do plan on correcting it?
Click to expand...

well, tomorrow (later today actually) i plan on filling the keggle a half gallon at a time to make reference marks on my stir paddle. perhaps i'll boil that water to get an actual +/- figure on boiloff.

as far as compensation, i figure i'll be low if anything. thanks to a post by ajf, i now know how to adjust pre-boil gravity by adding DME to achieve my desired OG (assuming i don't over boil or miscalculate final volume). i just entered the equations and examples in my NOTES in Beersmith (hopefully that giant bottle of DFH Red&White i just finished didn't cause me to screw 'em up). OTOH, i'll just consider myself luck if i happen to overshoot the pre-boil gravity.

thanks for everyone's input and advice!!!!
 
i thought i had read that you needed samples from each of the runnings, but never heard exactly why they needed to be split up like that
Click to expand...

As I wrote in another post today:

First runnings will give you an indication of how successful your starch conversion has been.
Preboil will give you an indication of how efficient your mash regime (mash and sparge) has been.
Pre-pitch will give you an overall figure to compare with final gravity to calculate alcohol volume and a benchmark to ensure fermentation has started.

I take pre-boil and OG only. Pre-boil is important because no matter what you do after that the ratio of gravity to volume will remain the same (until you start fermenting). You know what to expect from your wort and whether to boil longer (to get more gravity but less volume) or whether to consider adding more wort (either extract or mash) to compensate or whether to dilute.

Sometimes I forget to take pre-boil - while I recommend it you can make good beer without it. Good to do but don't sweat if you forget.
 
i'm gonna do Bobby_M's double batch sparge, but by the time i take 4 gravity samples (3 runnings and a total) i'm gonna be down a significant amount of wort. from what i'm understanding from most responses, the first runnings and the total pre-boil gravities are the most important. i'll probably just take those two and hope i don't need the other two.
 
lpdb185 said:
i'm gonna do Bobby_M's double batch sparge, but by the time i take 4 gravity samples (3 runnings and a total) i'm gonna be down a significant amount of wort. from what i'm understanding from most responses, the first runnings and the total pre-boil gravities are the most important. i'll probably just take those two and hope i don't need the other two.
Click to expand...

Yeah, I do a double batch sparge, too but don't take gravity readings from each running. With the first wort and pre-boil readings you can calculate your conversion efficiency and your overall lauter efficiency using Kai's spreadsheets.

When I started tracking the conversion and lauter efficiencies, I saw that my conversion efficiency was good but my lauter efficiency was poor. I started mashing a bit thicker to leave more sparge water and both efficiencies jumped. Now I'm getting about 92% into the boiler which is pretty high for batch sparging.

For other people, mashing thinner works out better. At least this way you can pin point where you're losing points rather than ending up with a low OG and wondering what went wrong.
 
kryolla said:
how do plan on fixing efficiency problems for your third runnings if your first and second are good?
Click to expand...

I just mentioned that since I've seen people ask for the gravity/volume of each running in threads where people are asking for help fixing low efficiency. I have no experience diagnosing efficiency problems myself.
 
EvilGnome6 said:
Yeah, I do a double batch sparge, too but don't take gravity readings from each running. With the first wort and pre-boil readings you can calculate your conversion efficiency and your overall lauter efficiency using Kai's spreadsheets.

When I started tracking the conversion and lauter efficiencies, I saw that my conversion efficiency was good but my lauter efficiency was poor. I started mashing a bit thicker to leave more sparge water and both efficiencies jumped. Now I'm getting about 92% into the boiler which is pretty high for batch sparging.

For other people, mashing thinner works out better. At least this way you can pin point where you're losing points rather than ending up with a low OG and wondering what went wrong.
Click to expand...

thanks, i'll look up that application and stick with just SG's on first runnings and total pre-boil (less for me to get confused about).

and yeah, i got confused about dumping the pre-boil samples when i was typing that last post :D.

thanks for all the help folks (just don't get mad when i have another question tomorrow :cross:).
 
I *heart* my refractometer. If I had bought it before I broke 3 hydrometers it would have paid for itself...
 
I can see taking a first runnings gravity reading to see if your getting conversion. If not keeo mashing. Once you have conversion on the first runnngs I'd just get your pre-boil reading. If your having problems maybe start to take more readings, but just starting out with all grain mashing and sparging I don't think you want to be screwing around with extra gravity readings. Its not hard, its just something else you have to do.
 

Similar threads

B
Very High Post Boil pH
2
Replies
48
Views
2K
Bassman2003
B
refect
Measuring Kettle PH
Replies
25
Views
1K
Indian_villager
I
K
Pre Boil gravity and how it relates to Temp
Replies
4
Views
836
kadozen
K
boondocksaint
10+ Point Difference in Gravity Readings?!
Replies
20
Views
1K
mggray87
M
hotbeer
What if you bring the malts slowly to mash temp?
Replies
14
Views
1K
hotbeer
hotbeer
InkBird 300

Latest posts

Back
Top