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Where did I go wrong?

Post #1 made 11 years ago
by kaiserben
G'day,

I'm a bit of a noob - this is only my third all grain batch.

I'd had a bit of a play with the Biabacus and was fairly sure I'd figured it out.

I decided to make a full volume BIAB batch of schwarzbier in my 19L pot from Big W. I decided on the following grain bill:

37% Pils Malt
37% Munich 2
18.5% Caramunich 2
4.5% Carapils
3% Carafa Special 2

I plugged (what I thought was) all the required info in into Biabacus (see attached) and bought the ingredients suggested. Today I went with all the suggested volumes - and pretty much hit everything spot on. Was really happy with the day.

But then I took a post-boil gravity reading when the wort was going into the no-chill cube (and I remembered to cool my sample to room temp).

I was expecting a reading around 1.050, but got 1.031. Where did I go wrong?

I plan to pitch the yeast tomorrow after it no-chills overnight.

More importantly I'm set to brew another batch tomorrow, an ESB which I also used the Biabacus to figure out how much grain to buy, and I'd like to try to correct whatever water volumes I need to to hit a more realistic OG for the style). Have added that file too.
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Post #2 made 11 years ago
by PistolPatch
Hi Ben,

Your BIABacus file is excellent. (Just maybe type in the AA% of the hops you will be using on the right hand side of Section D.)

There could be any number of reasons for the low gravity reading. The first thing to do though when you do get an odd reading, is to take another reading at a different time with the wort cool and well-mixed and using a hydrometer. It is not uncommon to get the occasional very dodgy reading.

So, take another reading before you pitch and after you have aerated the wort and shaken the fermentor.

If the second reading confirms the first, then this might be due to any of the reasons you see listed in this post.

Before Brewing the ESB...

1. See how the second reading goes on the schwarzbiert and if any of the things listed in the link ring any bells.

2. Double check the weight of your grain bill before mashing in. If someone else crushed it, check the weight with your kitchen or bathroom scales. This is the first thing to check.

3. Increase the mash time to 90 minutes (and preferably the boil time.)

4. Measure and record the first four fields in Section L on brew day if you are no-chilling. Add any cube trub to KFL after you transfer to cube from fermentor and at that time, record your VIF.

5. Make sure you cover and cool any hot gravity samples before you take a reading. Once cool measure and record GIB and GAW in Section M.

Let's see how that goes. :luck: tomorrow!
PP
Last edited by PistolPatch on 27 Sep 2014, 19:09, edited 1 time in total.
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Post #3 made 11 years ago
by kaiserben
I just pitched the yeast in that Schwarz.

And so I took the opportunity to take 2 more OG measurements using 2 different hydrometers and got readings of 1.032 and 1.034.

Out of the possibilities listed in your linked post none really stands out as the likely cause in my case. Although with "12. The grain is not being agitated during the mash.", can I ask if the following method should do what I need it to: I only opened & gave a quick stir twice during the first 75 mins, but for the following 15 minutes I did almost constant lifting/dunking/stirring/agitating as I let the stove get the mash temp up to 75 degrees C and then removed the bag (so it was kinda a 90 mash rather than 75 mins as it took the extra 15 minutes to get up to mash out temp). Good enough practice? Or should I be doing more agitating earlier on in the mash?

It also could have been the weight of the grains (a LHBS cracked them for me and I just assumed it was correct. I'll double check the grain for my ESB before mashing).
Last edited by kaiserben on 28 Sep 2014, 20:36, edited 1 time in total.

Post #4 made 11 years ago
by joshua
Ben, Did you get the desired 2.25 Gallon(8.5L), If your Volume was a bit High, AND the weight was low, your Numbers are Correct.

I do 12 Pack Volumes also, and the Volumes and Weights are very Important..A quart High or Low is a Large Offset with Specific Gravity.

The smaller mash Volume are Very Sensitive to Heat Pockets, I have found up to 20F difference between the Bottom of the Mash and the Top.

The small batches need Much More agitation then 5 gallon(19l) batches.

Also, Small Batches have Very Little Thermal Mass. My Mash temperatures can Drop 2 degrees every 10 minutes without Insulation.

I need to add heat every few minutes with a PID system to hold Mash temperature.

Some People may say Small Volumes Suck!!!
Honest Officer, I swear to Drunk, I am Not God.
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Post #5 made 11 years ago
by PistolPatch
I've assumed your Volume of Ambient Wort - VAW was close to estimated. If so Ben, it sounds as though there is nothing obviously wrong. That is enough stirring you did so there is nothing more you can do except put this batch down to being poorly weighed. If the same happens again (and you have made sure you have double-checked the grain bill weight) then we'll have to investigate things a little deeper.

On the next brew, try and type your actual numbers into Sections L to O. This makes the batch results quick/easy to picture.

:luck:
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Post #6 made 11 years ago
by kaiserben
It was very close to 8.5L (now slightly over 8L after it has cooled).

When you say "a bit" how much are we talking about?

My volumes were all quite close to the BIABacus' predictions (but the only volumes I actually measured properly were my initial volume of tap water to be heated for mashing and the VIF, the rest all looked about right).

One error I now think I might have made was that I initially used 15.32L of tap water (the SWN amount) - when perhaps I should actually have been using 15.02L (the TWN amount). Which should it have been? And, if I did indeed get that wrong, how much could that 300ml extra affect gravity?
Last edited by kaiserben on 28 Sep 2014, 22:20, edited 1 time in total.

Post #7 made 11 years ago
by kaiserben
I've attached the file with as many fields filled in as I could.

Some of the volumes are not exact (but are very reasonable estimates).
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Post #8 made 11 years ago
by joshua
Ben, A "bit" is 8.5L instead on 8L is 6% high, so Specific Gravity wound be 6% low or 1.047.

If the Grain bill was 4.0# instead of 4.09# the grain contribution was 2% low, so that would drop 1.050 to 1.049.

Not a great example, but a few ounces low on weight or High on Volume, can make a Bigger Difference on Small Batches, than 5 gallon Batches.

UPDATE: Looking at BIABacus PR1.3T - Schwarzbier - Schwarzbier 1 - Batch A0

The Volume of Ambient Wort(VAW) was projected to be 9.43L, and your Real VAW is 9.13L.

Just looking at Volumes you S.G should have been 3% higher than 1.05 or 1.051.

Numbers are just Numbers, But, My Figuring is way off.
Last edited by joshua on 28 Sep 2014, 22:22, edited 1 time in total.
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Post #9 made 11 years ago
by kaiserben
And I took fairly detailed notes of my process, so will put them here just in case it shows up a problem:

15.32L cold tap water put in pot and heated to strike temp.
Mash in and put lid on (and towels for insulation) at 67 degrees C.
40 minutes later check temp (and give it a stir) and it's 64C, so I put the stovetop on for 30 seconds and the temp gets back to 66C. Closed it all up again.
20 minutes later check temp (and give it a stir) and it's about 62C. Stove back on for 45 seconds and temp back up to 66C. Closed it all up again.
15 minutes later take towel insulation and the lid off, check temp (62C) and turn the heat on.
For the next 15 minutes I held the bag towards the top of the wort (off the bottom of the pot) and constantly either stirred, dunked the grain bag, and checked temp until it reached 75 degrees C - then removed the bag, gave it a bit of a squeeze. Guessed the pre-boil volume was fairly close to predicted.
27 minutes after removing the grain bag a rolling boil was achieved.
15 minutes later I put in the 60 minute hop addition.
50 minutes later I put in the 10 minute hop addition.
10 minutes later I turned the stove off.
3 minutes later I removed the 2 hop socks and then gave it a bit of a whirlpool.
10 minutes later I poured the wort into a cube with only a minute amount of trub going into the cube. Left about a litre of mostly trub in the kettle.
Before squeezing the cube it looked like there was 8.5L in there (according to the volume markers on the cube).
Just now when pitching the yeast it was a little bit over 8L (maybe 8.1L).

Post #10 made 11 years ago
by joshua
Ben, just a silly Question, did you use a Hydrometer??? if so, does it read 1.000 with Tap water.

If you used a Refactormeter, is the Calibration correct???
Honest Officer, I swear to Drunk, I am Not God.
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Post #12 made 11 years ago
by joshua
Ben, that means the Grain bill or the Mash temperature were too Low.

The grain could be 3# not 4#, which is WAY off by 25%.

Or if you Mashed in at 150F, you would need to be near 140F to have a S.G. at 1.031.

So, there are many things that can cause the Low Specific Gravity.....

Let the Beer finish off, and Enjoy what is called a "Session" beer, "A lot to drink, and not get Drunk"
Honest Officer, I swear to Drunk, I am Not God.
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Post #13 made 11 years ago
by HbgBill
I think the comment Joshua mentioned about heat pockets is very valid.. or, at least, it has been for me. On my last brew, I used an induction heater (IH) to help keep my mash temp up to snuff. I'd turn on the IH and stir a bit. Got the temp up to mash temp and covered. Opened about 10 min later to check and it was down quite a bit. Ultimately, I kept the heater on while constantly stirring until the temp probe was very equal in all spots. Then I covered the well insulated pot and cover.. THEN the temp remained very constant until the end of the mash. I ended up about 10 points lower than I expected.. and I think that most of that was due to too low a temp during much of the first half of the mash. I didn't keep the best of records on this first full volume mash.. but, I believe another part of that gravity difference was a bit too much wort that didn't boil off as completely as it should.

As with you, the next brew will be intense at record keeping. I'll continue this record keeping until I get my processes more nailed.
Bill
Hop Song Brewing-Santa Rosa, California

Post #14 made 11 years ago
by kaiserben
Yeah, it's the next brew I'm more concerned about. I can deal with having a weakish batch of schwarz (at least it tastes great).

In my mash process the temp went from 67 C (152F) to 62 C (143F), back up to 66 C (151F) and then down to 62 C (143F) again, then up to 75 C (167F) for mash out. So I guess there is that chance that mash temp was too low too often.

I think next time I'll overshoot my peak temps (maybe strike at 70 C, then each re-heat get it to 68-69C knowing it'll drop past my desired mash temp). And I'll also check & stir more often.

Post #15 made 11 years ago
by joshua
Ben, There is alpha and beta amylase, that the mash uses to convert Starch into Sugar...

See....http://realbeer.com/jjpalmer/ch14.html

If you can keep the mash near 65C/153F during the Mash, you will get the Best Conversion Possible.

If you can stir and check the mash Temperature every 20 minutes, you will have the Highest S.G. possible.

If you can Check your Thermometer against Ice(32F) and then Again at boiling(212F), you can trust that Thermometer.

I have 1 out of 4 that are good enough to use for brewing...What's the Problem with +-(8F).
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Post #16 made 11 years ago
by kaiserben
Hmmm. So reading that link, Palmer's 'How to Brew' about mashing, it seems my temps were all about right.

First thing I'll be doing now is double checking my thermometer. Because I'll tell you what; I now vaguely recall checking it in boiling water during a previous batch and noticing it was only 95C (203F), which would throw out the temps I believed I was mashing at.

(Note: Previous batch wasn't full volume biab. Completely different recipe and I had no idea what I was doing. It had a heftier grain bill and I added water to the boil, and more water into the fermenter to get my desired OG. So that previous batch didn't provide any similar warning signs to the schwarzbier batch I've just had the problem with).

Post #17 made 11 years ago
by PistolPatch
Ben,

In the link I gave earlier, this one, you'll see point number three reads...[center]
3. Thermometer not calibrated at mash temperatures. (This post shows how unreliable a single thermometer is.)
[/center] It's really important to have a few thermometers on hand. As you'll see from that link, accuracy at ice and boiling point does not mean accuracy at mash temps although you'll often read that is how to calibrate a thermometer.

Also see bundy's thread Thermometers - How to check your calibration at Mash temp. Don't blow yourself up!!!

Finally, don't over-shoot your strike temperature. It is better to be under and raise it.

Oh and make sure you measure both VIF and KFL on the next brew so as we can determine the all-critical VAW.

:peace:
Last edited by PistolPatch on 29 Sep 2014, 21:09, edited 1 time in total.
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Post #18 made 11 years ago
by kaiserben
Ah yes. I was reading Bundy's thread in past couple of days. I didn't want to go as far as boiling methanol/ethanol, but I guess it might come to that if my next batch has a similar problem.

It's annoying having bought equipment from a LHBS that might not be up to the task.

What I can certainly do is heat some plain water up to what my main thermometer reads as 65. Then check it against another thermometer I have (a candy thermometer). If they're out by more than a few degrees C I'll borrow a few thermometers from various mates and try to test if any are significantly different from the rest.

If I'm still worried by my results I'll get some ethanol or methanol. (I use an electric stove top anyway, so no naked flame).

And, of course, I'll most definitely measure and report back what happens in my next brew. I'm very appreciative of the advice/input from everyone here.

Where did I go wrong?

Post #19 made 11 years ago
by Contrarian
I wouldn't be too surprised that thermometers don't read precisely what they should, even when bought from a LHBS. I work in health an was chatting to the plumber at one I the local hospitals.

One of his jobs is to check the water temperature that is controlled by thermostatic mixing valves to be around 43C. I was eyeing off his thermometer while he was doing it as I could clearly see the application in my brewery.

The short story is that the thermometer itself is worth over $300 and he sends it away to be calibrated, usually at 40C every 6 months and he doesn't have supreme confidence in its accuracy across the temperature range.

The reality is that precision measuring devices for anything go up in cost based on their margin for error.

Don't despair though, within 2-3C is unlikely to ruin a brew and by tasting your results you'll get an idea of what works for you with your equipment, that's the most important thing!

Post #20 made 11 years ago
by kaiserben
So it's now 4 and a bit days since I pitched the yeast.

Gravity is down to 1.013, which was the expected FG if I'd managed to hit my target OG of 1.050 (instead I got OG of 1.032).

Should I expect it to go down much further?

I will have had some wildly fluctuating ferment temps between 10-18 C, so perhaps it's fermented as quickly as an ale rather than a lager? I suppose, after determining if ferment has finished, I'll put in secondary and try to get it nice and chilled before bottling? (beer will end up in PET bottles).

Post #23 made 11 years ago
by Mad_Scientist
That's the calculator I used.

There is no way to know what the final will be, there are factors such as grain bill, mash temperature, yeast viability, yeast cell count, etc.

Just hope for something in that range.
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Post #24 made 11 years ago
by PistolPatch
This is a good example of a thread that many lurkers here could answer really well. As MS said above, FG relies on many things. Also single hydrometer readings can't be trusted. I think I addressed and answered this question in the last week somewhere in this thread. Does that thread help?
Last edited by PistolPatch on 03 Oct 2014, 21:00, edited 1 time in total.
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Post #25 made 11 years ago
by kaiserben
PistolPatch wrote:I think I addressed and answered this question in the last week somewhere in this thread. Does that thread help?
Yeah (if you mean your post about taking a sample and keeping it alongside the FV), that was really handy info.

I couldn't help myself, and drank my last sample though (it was so very tasty).
Last edited by kaiserben on 04 Oct 2014, 11:46, edited 2 times in total.
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