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Old 03-27-2012, 09:53 PM   #1
mudlark
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Default Consistently high final gravity

Ever since I began doing all-grain mashes, I have been having very high final gravities. My second to last batch is very sweet and I decided to finally see what I could do about it. I am trying to fix that batch (an IPA) and also gather some useful data on my newest batch (a Rye IPA):

First, the IPA:
78% 10.5lb American Two-row Pale
11% 1.5lb Wheat Malt
7% 1lb Flaked Barley
4% 0.5lb CaraVienne

The mash was 60 minutes at 154 degrees and I used iodine tests to confirm that the conversion was complete. I got about 70% efficiency. OG was 1.069 and the FG was 1.026. It was supposed to be down in the 1.017 area. I am using both a hydrometer and a refractometer to measure the gravities. I used some yeast that I had gotten from a local brewery. I had used this yeast in a stout previously (OG 1.048 FG 1.020 also higher than estimated) and racked the IPA on top of the trub from the stout's primary. Probably not the smartest thing to do but I didn't have the time or inclination to wash it just then.

I oxygenated the wort prior to pitching by dumping it back and forth between two buckets a few times. After one week it hit the FG above, I washed the yeast from the primary this time and stored it in the fridge and I racked the beer to a carboy and it hasn't moved since. Looking back, it seems like I racked too soon. I tossed some washed yeast back into the carboy hoping that it would continue fermenting, but it hasn't done anything in the last 2 days.

This last weekend I did the rye IPA:
52% 8lb American Two-row Pale
32% 5lb Rye Malt
6% 1lb Flaked Rye
6% 1lb Flaked Barley
3% 0.5lb CaraVienne

This time I did a starter 24 hours before. I used 1 cup DME in about a liter of water, some of my washed yeast and let the stuff get started overnight.

I mashed for about 80 minutes at 152 degrees and got complete conversion indication from the iodine test. The OG was 1.060, about 60% efficiency. This time I did a fast ferment test too. I took about a cup of wort and added 1/2 tsp of bread yeast. It's been going for two days and is showing a pretty lousy final gravity: 1.026. Maybe its not done yet...

I've been shaking/agitating the carboy, the ferment test and the bucket with the new beer, and I think I'm concluding that my mash is the problem here. All my batches' FG have been too high (not just the three I described here) and the only common denominator is the mash. I've used dry yeasts, liquid yeasts and the yeast from the brewery and now bread yeast too.

If this is the case what can I do next? I have 2 10 gallon coleman coolers and am using a CPVC manifold in the mash tun and a CPVC 'sprinkler' on the HLT. I usually use hopville's calculator to find the strike temp, dump in the grain, mix it up, make sure its between 150-154 degrees, leave it for 20 minutes and then give it a little going over with a long spoon, leave it for another 20, then cut it up again, then leave it for the final 20 or so. I set up the HLT with 5 gallons of water at about 180 degrees and then just sparge the whole thing very slowly (30 minutes or so?). I get about 6.5 gallons out then toss it on the flame.

Is it possible that I am getting way too many unfermentables out of the mash? Could this explain the high FG? Can I do some tests to confirm that my mash technique is to blame? I could do some small scale stuff but I figured some hints might get me going in the right direction.

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Old 03-27-2012, 09:56 PM   #2
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Interesting. Your mash process seems fine, assuming your temp readings are accurate. What do your fermentation temps and times look like?

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Old 03-27-2012, 10:08 PM   #3
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I use an immersion chiller to get the wort down to ~70 degrees and pitch the yeast. The fermentation takes place in the corner of my kitchen at about 68 degrees.

As for the times, I usually do 1 week in the 6 gallon bucket and then 1 week in the 5 gallon carboy. At that point I keg it, do a little force carbonating and test it out. Usually the FG is high and the taste is young, but its drinkable and over the next week or so in my kegerator the flavors mellow into something pretty tasty.

I was just reviewing my recipes and it looks like I have had 1 or 2 batches that got down to an expected FG but my note taking is not great and I don't know what differences there might have been in the process. The yeast I used in those was just the regular wyeast ale 1056 and they got down to about 1.012 and 1.014. Some batches after that had dannstar nottingham and those had pretty high FGs. It looks like I did have one batch with Dannstar that got down to 1.016 but the rest are all between 1.018 and 1.022, higher than the estimates. As I said above, the last two batches used the yeast from the brewery and those were high and my most recent batch is also looking high in the ferment test.

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Old 03-27-2012, 10:14 PM   #4
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Quote:
Originally Posted by mudlark View Post

As for the times, I usually do 1 week in the 6 gallon bucket and then 1 week in the 5 gallon carboy. .
Maybe try leaving it in the primary a bit longer..

EDIT: After reading your OP again I noticed you mentioned your beer tastes sweet. Now I'm wondering if maybe your thermometer needs to be calibrated, and you might actually be mashing at a higher temp than you think you are. That will give you more unfermentables which will result in more sweetness and a higher FG..
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Old 03-27-2012, 10:29 PM   #5
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Thanks, I will definitely do that. I wish I had better notes from my previous batches to see if the good FG beers had a few extra days in the primary or something like that. My current batch will not leave the primary until I am satisfied that it is totally done fermenting.

If the batch in my carboy picks up some activity from the yeast I pitched in then this will also confirm that I have just been racking too soon. We'll see.

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Old 03-27-2012, 10:40 PM   #6
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I may have edited my post before you responded.. NOTE the edit above.. What type of thermometer do you use to check mash temps?

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Old 03-27-2012, 10:46 PM   #7
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I am using this .

It's had some rough times though and in fact it has been slammed in a drawer once or twice and has a bit of a kink. I think I checked it when that happened but I'll try to confirm again that its accurate. Thanks!

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Old 03-27-2012, 10:58 PM   #8
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I use a lab thermometer for my brewing as it responds quickly, doesn't use batteries, I very accurate and super cheap.

You should always verify your thermometer is correctly calibrated. You can do this by placing the thermometer in an ice water bath and verifying it is about 32 F and then placing it in boiling water to verify it at 212 F. If its incorrect at these values a dial thermometer can be calibrated by adjusting the nut on the back of the face.

My guess is that your thermometer is incorrect but it could be other factors too. Do you know which yeast the brewery gave you?

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Old 03-27-2012, 11:15 PM   #9
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I've checked the thermometer at boiling and its ok and it also matched up well with a few other thermometers at the 150ish range and room temperature. In the ice bath it was reading 35 while my other digital thermometer was reading 32.1 so that's strange. I should probably replace it but I don't know if its the source of the issue.

I wonder though, in recent batches I have been a little lazy about the temp in my HLT. Let's just say for instance that the temp in there was closer to 200 than 180 and I sparged with it for 30 minutes, could that pull out a lot more unfermentables than expected? This is purely hypothetical of course..

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Old 03-27-2012, 11:18 PM   #10
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Quote:
Originally Posted by TarheelBrew13 View Post
I use a lab thermometer for my brewing as it responds quickly, doesn't use batteries, I very accurate and super cheap.

You should always verify your thermometer is correctly calibrated. You can do this by placing the thermometer in an ice water bath and verifying it is about 32 F and then placing it in boiling water to verify it at 212 F. If its incorrect at these values a dial thermometer can be calibrated by adjusting the nut on the back of the face.

My guess is that your thermometer is incorrect but it could be other factors too. Do you know which yeast the brewery gave you?
Actually if you want to calibrate your thermometer with boiling water you have to find out what temperature water boils at your geographic elevation. At my elevation water boils at about 206F, so all of my thermometers are calibrated to this. You can find your elevation and an elevation/boil temp calculator via google or bing...
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