Trouble Shooting

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Trouble Shooting

Post  Harker on Thu Apr 09, 2009 11:18 am

Alright Brewmen,

Tell me why I am such a shitty brewer. I'll give you the specs and you tell me the problem. I have been missing my original gravity by approximately 6-8 points (low) for the last couple beers I made. I have some ideas but I can't pinpoint the problem. We will start by analyzing my last beer which was my "dirty blonde". Here is what you need to know:

anticipated og: 48
malt: 10.3 lbs
expected mash rest: 152 degree (after adding 166 degree at 1.33 water to grain ratio).
Pre boil volume: no problems here, I collected 7 gallons which was exactly what I was aiming for.
Final volume: I was shooting for 5 gallons, but ended with 5.5 gallons
Sparging: 4.5 gallons at 169 degrees single batch

First of all, after my grain/water infusion my temperature was 149 degrees (3 points low). I added 1/2 gallon of boiling water to bring it up to 151 or so.

I collect exactly 7 gallons of wort which is exactly was I was trying for.

Part way through the boil I checked the og at 60 degrees, it read 1.041 (7 points low)

I added 1/2 lb of dme to the last 20 minutes of the boil, this brought the og to 1.048 measured at 70 degrees (exactly what I was shooting for, which should not have happened with just 1/2 pound of dme).

My boil was weak cuz of a poor flame, and I account for 15% evaporation rate, but I collected 5.5 gallons in the fermenter when I should have only had 4.96 gallons.


I think that my barley crusher might be set wrong. Do you think that I am crushing too course?
Jim thinks that my flow might be too fast when I am collecting my wort.
What's up with my process?

Carnes you had this problem once, I remember when you were continually getting low efficiency for a while. What was the problem then?
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Trouble Shooting...

Post  scribe on Thu Apr 09, 2009 11:59 am

So, I ran your specs on Beer Alchemy (Macintosh ProTools Equivalent). And yes, it looks like before you added the 1/2 lb. of DME you were getting between 65--68% efficiency. Now, to deter the debate as to whether these software programs are lying to us about our efficiency (according to Rich) I think it's at least safe to say that your efficiency as of late is less than it once was (regardless of the actual percentage). Here are the normal questions I would pose:

1. How's the mineral content of your water? (e.g., distilled water will effect efficiency considerably).
2. The mill grind? I don't think too fine would give you less efficiency though. You told me that you were scared it was too powdery. If that's the case, you would extract tannins from the husks, but would get a greater efficiency. Correct me if I'm wrong, guys, but that's the problem with too fine, I believe. Too coarse of a grind would give you a less efficient conversion.
3. Barging sucks. Okay, just kidding!! Granted you could probably get 5% more efficiency with Flarging, but this would get you up to 73%--and according to Beer Alchemy--I haven't hit below 80% in a long time with my Flarging (again, let's spare the debate on whether it's actually 80% or an exaggerated software issue). Even with batch sparging, I would think you should be hitting 73-75%, not 65-68%.
Now, not to start a debate over mills either, but I know that every time I used Bill's Schmidling Grind I hit between 80-85%. That's why I bought one. You could try mine for your next batch just to see if there is any variance. (The Schmidling has no adjusting knob). This way you could at least begin to isolate your issue. If it is your grind.. then we could focus on that.
4. Sparging too fast? I'm not sure if I buy this. Every youtube video I've seen on barging shows the brewer doing a rest, then collecting within a few minutes. However, Jim might be able to explain this a little better, but I thought the purpose in doing a batch sparge removed the need to collect slowly by adding 170 degree water to the grain bed, extracting the sugars from the husks immediately, then collecting quickly. I will say, from my experience, the closer my grain bed gets to 170-175, the more I extract. For my wheat wine, I used 185F sparge water at first, getting my grain bed to 170 quite quickly, then sparged with 175F for the rest. For a half-hour collection I was able to hit 84%. So, temp of grain bed during collection might be a factor.

Okay... who else wants to chime in here.
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Re: Trouble Shooting

Post  Librarian on Thu Apr 09, 2009 1:00 pm

I think you actually hit a bit higher than the mash efficiency you planned on!

Your OG was 1.048, but you told me yesterday that you measured that at 70F. So your actual OG at 60F would be 1.049.

You were shootin for a total gravity of (5gal)x(48 points) = 240 total points. You ended up with 5.5 gal at 1.049, or (5.5gal)x(49 points) = 269.5 total points.

DME should give you about 45 points per pound per gallon. You added 0.5 pounds, which should have accounted for 22.5 total points of your OG: 269.5-22.5 = 247 total points.

I think the problem was that you didn't account for volume when you measured your gravity at 1.041 during the boil. Assuming you were halfway through the boil (I thought that's what you said yesterday), you would have had about 6.25 gallons. (6.25gal)x(41 points)=256 total points. Boiling this down to 5 gallons would have givin you an OG of 1.051. Boiling down to 5.5 gallons should have given you 1.047.

So you can see that you have to figure in the current volume. Both ways you figure it you got higher efficiency than you planned. There is a bit of a discrepancy with how much the DME added though, did you add exactly 0.5 pounds?
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Trouble shooting

Post  Porter on Sat Apr 11, 2009 3:53 pm

I think Carnes hit the proverbial nail on the head with his response. The problem was not in the process, rather in the Harker's noggin. He has been taking the gravity of the pre-boil wort and complaining that it is lower than his expected OG. The fact that 1-2 gallons of water gets boiled out of that volume, would naturally increase the gravity of the wort. As to the flow rate issue, when I first started with all-grain brewing (and I was still in the dark "barging" stage of my life) I opened the spigot wide open to collect wort and I ended up with around 62% efficiency for my 1st couple batches. I then switched and started collecting much more slowly, and efficiency improved to around 70%. Also (and take this for what it's worth) Charlie Papazian said in The Home Brewer's companion that when it comes to flow rate faster is not better and it should ideally take 20-30 minutes to collect the initial runnings. I guess it's one of those deals where you should just find and stick to a method that has been consistent and effective for you. If that method involves collecting in 2 minutes, go for it!
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Good stuff!

Post  Harker on Mon Apr 13, 2009 2:29 pm

Well, Im an idiot. I am not sure why, but I was not looking at my pre-boil gravity number when I made the decision to add DME. After I went back to review, I hit my og exactly at 1.041 with 70% efficiency. I feel like an idiot. Anyway, it turned out being a blessing in disguise. I had a problem with my burner which caused me to boil off only 1 gallon instead of 1. The extra DME I added to the boil compensated for the poor boil. I hit my post-boil gravity exactly. That's some divine intervention if I've ever seen it.

Despite this last screw up, I still had problems with my last beer quest beer (wheat ipa). I was about 8 points low on the post-boil gravity. This is in part because I configured my recipe around 75% efficiency when I'm only getting 70%. As expected, it finishes really bitter due to the high IBU's and the 1.008 fg. Also, all of my hop flavor and aroma dissapeared as it carbonated. Oh well, it may not be beer quest material, but it is still drinkable.

Thanks for the trouble shooting guys. It really was helpful.
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Re: Trouble Shooting

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