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Major Brewing Screwup

Post #1 made 16 years ago
by shibolet
Hi all
so here's my story:
I've been BIABing for a few months now. I use an electric iron pot (not really an "urn". i think it was once used to do laundry). the volume is aprx. 47 liters.
the pot has a hidden heating element that runs through a cylinder at the bottom of the pot. i think it probably takes up about 1-1.5 lites of space.
so far i have been using the original "BIAB_Equipment_Set_Up_Volumes.xls" that only has one worksheet. also, i have been using a tape-measure to estimate the volume in the put (based on the spreadsheet).
i have always set the "End of Boil Volume (Batch Size)" to 23L and used the same value on my recipe calculator (i use the online Recipator).
so far i have been getting very good efficiency (at least 80%) and have usually ended up with at least 21 liters of finished beer. My last brew was an Oatmeal Stout, i ended up with 66 0.33L bottles (!). but the OG was 1047 instead of 1052. on the other hand it ended at 1007 instead of 1012. so something in my system is off.
i am quite sure that the tape-measure was not giving me an accurate measurement.

well, i thought that the new and improved spreadsheet would work better. so i downloaded the "Calculator.xls" and set up my next three brews on it. i also bought a wooden stick and collaborated it to use as a dip-stick in my pot.
so i went ahead and brewed another batch. Whisky Barrel Porter. what a fuck-up!
the calculator transformed the recipe to a 27 liter batch and i did what it said (grain bill and hops).
the calculator called for 39.4 liters, so started out with around 37 liters figuring i could add more later.
mash went fine, pulled the bag, drained it and measured 35 liters priboil. the calculator said 34.8L, so i guess thats all good. however, the priboil gravity was 1041 instead of 1044. that's an efficiency difference of about 4% (75% instead of an expected 79%) that could be explained by the fact that i did not ask the HBS to crush my grains twice as i have asked for in the past.
so i went on to boil for 90 minutes. after the boil i measured 32 liters. the calculator said 27. oh shit!
so i boiled a bit longer but it was late and i was fed-up.
i ended up with an OG of 1044 instead of an expected 1056 and with 23 liters in the cube and another 8(ish) in the kettle (that went down the drain).

apparently, in the past brews my volume measurements were crap. i will recheck the calibration of the dip-stick. i also think my boil-off rate is way lower that the 5.11 lts/hr used by the calculator.

[i will attempt to fix this batch by adding half a kilo of hydrated DME to the wort when going into the fermenter, that should add around 7.5 gravity points]

also, as of yesterday, i am the proud owner of a refractometer, to the next time, pri-boil, mid-boil and post-boil gravity measurements should be much easier to do.

any thoughts?
Last edited by shibolet on 31 Aug 2010, 21:07, edited 5 times in total.
Cube:
fermenter: Sourdough Spelt Ale, Classic Lambic, Oud Brune, Barrel Aged Belgian Dubbel
Kegs: Bob's Black IPA, Blanc Blond, Soda...
to be brewed:

Post #2 made 16 years ago
by BobBrews
shibolet,
here is my two cents worth (not much) Even though I have a keggel that can hold 15 gallons I most always brew 5 gal.(19) liter. So I know that I want to fill my ferment bucket to the 5 gallon mark. I fill my pot about an inch above a weld in my keggle wall and boil down to the weld to get 5 gallons of wort. Not stick to measure. If I have a 90 minute boil I may add a little more water. I don't worry about trying to follow a spreadsheet to calculate water amounts because I only have to fill a 5 gallon cube and then primary fermenter.
I don't take gravity readings because of a (slight) chance of infection and the bother. It's like this for me. If I see a good fermentation that last's three days or so I know it's done I wait a couple of weeks more for the bucket to clear up and then I keg. "No fuss no muss" If I hit my temperatures and the ferment was good my gravity will be close enough to the expected readings.
Yes, I am LAZY. I have learned that beer is my friend because it is very forgiving. I know that I may not reproduce a recipe exactly but that's the fun for me because I just keep brewing different recipe's.
So here is the short version "Don't worry about the small stuff. You are a good brewer and everything will turn out OK" If it doesn't? you can always cook with it! Keep on brewing!
tap 1 Raspberry wine
tap 2 Bourbon Barrel Porter
tap 3 Czech Pilsner
tap 4 Triple IPA 11% ABV
Pipeline: Mulled Cider 10% ABV

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Post #3 made 16 years ago
by hashie
I've gotta agree with Bob, don't sweat the small stuff!

I also don't take any readings on gravity during mash or boil. I wait until I empty the cube into the fermenter and then take a reading. I can always work backwards from here if I want to know what my pre-boil gravity was.

In the end, take this as a learning experience. You are learning what your boil off rate is. From this you can calculate what starting volume you need for your system to end up with 23 litres of wort.

Regardless of what OG you get into the fermenter, it will still be beer.
"It's beer Jim, but not as we know it."

Post #4 made 16 years ago
by mike
It took me quite a few batches to calibrate my system. I had a problem with my volume post boil, when I would siphon into my carboy i was trying to leave as much trub as possible in the kettle and would end up with less in the fermenter than I wanted. I discovered the scale button on my beersmith software and just added another gallon to my desired volume at the end of boil. It automatically adjust your hop and grain bill so you will have the same gravity and ibu's as your old batch size. I check my preboil gravity with a refractometer as well toward the end of the boil. If my gravity looks like it will be a little low, I just boil a little longer until I end up where I want to be.

Post #5 made 16 years ago
by widdley
Since PPs not around, I'm going to try and channel his wisdom :ugeek: , and if anything below is incorrect blame him :P

Firstly, if you've still got all your fingers and the house didn't burn down then its not really a major screw-up ;)

Your 'urn' looks a similar shape to mine (mine has a diameter of 38 cm, I'm assuming yours is 39 cm ?). I find with a good rolling boil I get an evaporation rate of just under 5 L per hr - close to what is predicted by the calculator.

According to your figures above, your pre- and post-boil volumes were 35 and 32 L respectively meaning you only boiled off 3 L in 90 minutes ? Which (in my infinite lack of experience) is pretty low :?

This appears to be the only reason why you got the calculation discrepancy with the spreadsheet. So you either need to increase your boiling vigour or modify the spreadsheet to suit your evaporation rate. The latter is easier, but there are good arguments for doing the former! E.g. carrying away nasty volatiles like DMS etc

Like the others have said, the best way to avoid gravity discrepancies is to leave your hydrometer / refractometer somewhere inaccessible :o

This is sage advice because specific gravity is affected by a whole range of things including but not limited to extraction efficiency, which in itself fluctuates just because...and is why we calculate an average. Different grains also have different theoretical maximum amounts of sugars that can be extracted, but the reported numbers are only averages because the actual values will vary depending on the growing season and origin of the grain, and because nature likes to do that shit. You also need to take into account whether your HBS painstakingly measured out exactly 155g of Carafa III etc or just around about that much...

Hence the formula for calculating your expected original gravity as actually: :o :x :oops: :cry:
Guess of how much grain you actually started with
Multiplied by
Guess of how much sugar is available for extraction
Multiplied by
Guess of how efficient your system will be at extracting these sugars on a particular day
Multiplied by
Random error associated with your hydrometer and other measurement tools probably not being precision scientific instruments anyway

So from my point of view if you end up with roughly the right gravity then everything's probably OK. However, if you really want to be spot on then do the following:
1. start with a few litres less total liquor, as it’s a lot easier to add some water later rather than having to remove it.
2. at the start of the boil measure your gravity and volume and calculate total gravity units:
3. divide the total gravity units by your desired original gravity (in gravity units), which will give you the number of litres of wort you can make (target end boil volume)
4. or instead of 3 calculate how much DME etc to add to raise total gravity to meet the desired end boil volume
5. boil away, and towards the end of the boil top up the kettle to the desired target end boil volume

That all said, at the end of the day the only real measurement that is truly useful is the final taste test. If it tastes good to you then all the measurements were by definition spot on :D

Post #6 made 16 years ago
by shibolet
widdley,
thanks for taking the time to write such a detailed reply.
...and other measurement tools probably not being precision scientific instruments anyway
LOL. i should post a photo of my dip-stick.

i was contemplating doing exactly as you suggested,
start with a few litres less total liquor and top up to the expected OG towards the end of the boil. that seems to be the best way to go in this case.

my pot only has a plug that fits into the heating element. not dial or thermostat. so i can't really up the boil at all.

i guess if you want to be more accurate with the grain weight and crush you've got to do your own milling. i'me not going there just yet.
Last edited by shibolet on 01 Sep 2010, 17:29, edited 5 times in total.
Cube:
fermenter: Sourdough Spelt Ale, Classic Lambic, Oud Brune, Barrel Aged Belgian Dubbel
Kegs: Bob's Black IPA, Blanc Blond, Soda...
to be brewed:

Post #7 made 16 years ago
by PistolPatch
widdley wrote:Since PPs not around, I'm going to try and channel his wisdom :ugeek: , and if anything below is incorrect blame him :P
:o

LOL widdley! Great post too... Love your advice on putting the refractometer somewhere inaccessible :P. (Another good trick with the hydro is if your gravity is too low, use one finger to push it further into the hydro tube until it reads right. If too high, use 2 fingers to pull it up so it reads right. Works every time!)

shibolet: There is a lot of sense in what widdley and the others have written. Certainly don't take one brews figures too seriously. The gravity estimates on the Calculator aren't that accurate - it's only within about 4 points. You might be better using the reciprocator for your gravity estimates.

If you still have your figures from your first brews, I'd be looking over them and over-riding the necessary cells in the calculator to suit as suggested by widdley. I also agree that your evap rate does sound pretty low.

The only real answer is to brew again. I think you are doing the right thing by taking lots of measurements and shouldn't throw away your hydrometer just yet :) - it is important to get to know how your system behaves but it is equally important not to get worried about the measurements on one brew as so many things can go wrong as also mentioned above.

Be careful using your refractometer. Readings can vary a fair bit with temperature, time, clarity of wort and air bubbles - they are designed to measure cool grape juice so use it in conjunction with your hydro until you get confident and consistent in your reading of it.

I hope I have written more than widdley.

:)
PP
Last edited by PistolPatch on 01 Sep 2010, 17:34, edited 5 times in total.
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Post #8 made 16 years ago
by shibolet
i thought of going back to my notes but i guess i changed to many variables on this one brew to be able to compare: the Calculator, the dipstick, the recipe.
oh, well. i will just have to brew again. very very soon.
Weyermann Smoked Mild
Last edited by shibolet on 01 Sep 2010, 18:10, edited 5 times in total.
Cube:
fermenter: Sourdough Spelt Ale, Classic Lambic, Oud Brune, Barrel Aged Belgian Dubbel
Kegs: Bob's Black IPA, Blanc Blond, Soda...
to be brewed:

Post #9 made 16 years ago
by widdley
shibolet wrote:my pot only has a plug that fits into the heating element. not dial or thermostat. so i can't really up the boil at all.
You really need a good rolling boil... Or so I'm led to believe ;)
There was a recent topic on the AHB forum LINK HERE which is worth a read... There is a lot of arm waiving, but some pretty good points shine through :lol:

If you can't modify your kettles heating ability you can always boost it with an over the side heating element: but make sure you plug it into a different power circuit to the one your urn is on, or you'll blow your fuses.
heater.jpg
PistolPatch wrote: Another good trick with the hydro is if your gravity is too low, use one finger to push it further into the hydro tube until it reads right. If too high, use 2 fingers to pull it up so it reads right. Works every time!
:lol: Wouldn't it be great to write an alternate 'brewing guide' that contained gems of advice like this... Best Seller me thinks :D
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Last edited by widdley on 02 Sep 2010, 10:08, edited 5 times in total.

Post #10 made 16 years ago
by PistolPatch
shibolet wrote:I thought of going back to my notes but I guess I changed to many variables on this one brew to be able to compare...[/url]
Yep, changing even more than one variable on a single brew can get really confusing if you are unlucky enough to strike a problem :roll:. I had a small infection problem once that took me an embarrassingly long time to solve. If I had kept some decent notes, I would have found it a lot faster.
widdley wrote:Wouldn't it be great to write an alternate 'brewing guide'... Best Seller me thinks :D
Now that would be fun :). With you on board, I can see this being a real possibility. There's already some great material available. The post I copied here written by Chris on weighing grain is one of the best I have seen and I re-read it often. The link in that post leads to some other goodies. We should think more on this :idea: .

Excuse the off-topic bit shibo ;)
Last edited by PistolPatch on 03 Sep 2010, 20:44, edited 5 times in total.
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Post #11 made 16 years ago
by wizard78
PistolPatch wrote: If I had kept some decent notes, I would have found it a lot faster.
Crap, keeping notes, thats what I forgot to do. :? I wrote a note to remind myself.....but forgot where I put it. :lol:
Last edited by wizard78 on 03 Sep 2010, 21:28, edited 5 times in total.
[center]"All right, brain. You don't like me and I don't like you, but let's just do this and I can get back to killing you with beer."
[/center]
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Post #12 made 16 years ago
by PistolPatch
wizard78 wrote: Crap, keeping notes, thats what I forgot to do. :? I wrote a note to remind myself.....but forgot where I put it. :lol:
What you say is funny wiz but it gets even worse!!! I actually often do take good notes while I am brewing but they always get lost afterwards.

You work on your auto-syphon and I'll work on a note-keeping method for BIAB!

Apologies again shibo :).
Last edited by PistolPatch on 03 Sep 2010, 23:24, edited 5 times in total.
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