[trapae]

 So I feel like I get consistently low final gravities but I just dumped trub ( after 12 days of fermentation ), and took a final gravity reading from my conical fermenter and it was the lowest I've ever had=1.005.   I have brewed this exact recipe several times and I usually get 1.008 to 1.010.   And I did nothing differently.   I tested my hydrometer on some arrowhead spring water I had ( did not have any distilled) to make sure it was accurate before taking the reading.   First five days I fermented at 65, then up to 68 for 3-4, then at 70 until now.   My original gravity was 1.063.
Here is the recipe below. Does this make any sense to anyone?

Batch Size: 6.33 gal   Style: American IPA (14B)
Boil Size: 8.50 gal   Style Guide: BJCP 2008
Color: 6.0 SRM
Bitterness: 62.0 IBUs   Boil Time: 60 min
Est OG: 1.062 (15.2° P)
Est FG: 1.013 SG
ABV: 6.4%

Mash 60 min @ 150

Ingredients
Amount   Name   Type   #
10.82 g   Gypsum (Calcium Sulfate) (Mash 60 min)
13 lbs 5.40 oz   Pale Malt (2 Row) US (2.0 SRM)
9.19 oz   Cara-Pils/Dextrine (2.0 SRM)
9.19 oz   Caramel/Crystal Malt - 40L (40.0 SRM)&
0.54 oz   Magnum [14.0%] - Boil 60 min
0.80 oz   El Dorado [15.0%] - Boil 15 min
0.45 oz   Centennial [10.0%] - Boil 15 min
0.30 oz   Columbus/Tomahawk/Zeus (CTZ) [15.5%] - Boil 15 min
1.08   Whirlfloc Tablet (Boil 15 min)
1.00 tsp   Yeast Nutrient (Boil 15 min)
1.00   Chiller/whirlpool (Boil 10 min)
0.50 oz   Columbus/Tomahawk/Zeus (CTZ) [15.5%] - Boil 7 min
0.30 oz   El Dorado [15.0%] - Boil 7 min
0.20 oz   Centennial [10.0%] - Boil 7 min
Starter   California Ale (White Labs #WLP001)

At flameout, cool quickly to 175 and then whirlpool hop for 30 minutes: 0.8 oz Columbus 2.05 oz Centennial 2.75 oz El Dorado

[trapae]

PS:  the yeast packets I used was quite old so for my starter I used the BrauKaiser equation instead of the white equation for the first time so it's possible I could've had quite a bit more yeast cells then usual. Don't know if this  would make any difference.

[PharmBrewer]

Any idea what your pH was?  I have heard it can affect yeast attenuation towards the end.

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[PharmBrewer]

Any idea what your pH was?  I have heard it can affect yeast attenuation towards the end.

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"Nutrient uptake by yeast

Shortly after being pitched into fresh wort yeast will start lowering the pH of the surrounding medium (i.e. beer). This is the result of ammonium ion and amino acid uptake, secretion of organic acids [Briggs, 2004] and most importantly a proton pump which moves H+ ions from the yeast cell into the beer. By doing so the yeast also raises its internal pH. This proton pump is very important to the yeast and it is the most abundant protein in its cell membrane [Briggs, 2004]. The resulting pH gradient through the yeast's cell wall facilitates the uptake of nutrients like maltose.

Maltose uptake is a proton symport process through the cell membrane. The proton concentration outside the cell is greater (lower pH) than inside the cell (higher pH) and therefore a natural gradient exists which encourages protons to flow from the outside to the inside of the cell. Though the use of a symporter, a cell membrane protein, maltose can “piggy back” on the flow of protons into the cell. This is one of the reasons why yeast cells do better in an acidic environment and have means of lowering the pH.

[http://braukaiser]

The ability of yeast to lower the beer’s pH is important for healthy and low yeast stress fermentation and is one of the reasons why sufficient pitching rates are important and why it is better to step up starters rather than starting a small amount of yeast in a large starter. The more yeast cells that are working on lowering the pH the faster the pH will be able to drop.

As yeasts age, starve or otherwise loose their vitality, it becomes increasingly difficult for them to pump H+ from their cells into the beer. After all, this goes against nature’s desire to equalize everything and therefore takes energy. The result is a slight rise of the beer pH after primary fermentation. The pH can rise more significantly if the beer is not taken off the yeast before a large number of yeast cells start to autolyze."

http://braukaiser.com/wiki/index.php?title=How_pH_affects_brewing



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[trapae]

 Mash pH was 5.4. Never taken pH from the fermenter.   Just hope the beer doesn't taste like hop water because of the low FG.

[HoosierBrew]

I like a well attenuated IPA @ 1.010, but 1.008 is fairly thin. Next time try mashing the same recipe at 153F. And I assume you corrected your readings for temp?
 

[morticaixavier]

Unless your thermo is way off I find it hard to believe it's the mash temp causing the problem. I notice attenuation differences when mashing at different temps but they are not huge.

My first thought with unexpectedly high attenuation is contamination with a more attenuative yeast and/or bacteria.

I suppose there may also be variation in the Malt composition. did you use the same maltsters products across batches?

[HoosierBrew]

Unless your thermo is way off I find it hard to believe it's the mash temp causing the problem. I notice attenuation differences when mashing at different temps but they are not huge.

My first thought with unexpectedly high attenuation is contamination with a more attenuative yeast and/or bacteria.

I suppose there may also be variation in the Malt composition. did you use the same maltsters products across batches?

I don't disagree, Jonathan. All things being equal, raising mash temp by 3 dF could well bump his FG a point  or two, probably all he needs

[pete b]

John, I gather from your two posts that you are under the impression the FG was 1.008. It was 1.005.
Trapae: how's it taste, what's the body like? If its not too thin I wouldn't discount a measurement error.
If it tastes off infection is possible of course.
If its not infected and too thin I would try adding some munich or vienna to the base malt and/ or a touch more crystal and mash in mid 150's.
EDIT: for my personal taste I wouldn't add more crystal, just munich or vienna at 20%ish of a base blend.

[trapae]

 Actually I didn't think of that. This was the first time I ordered my malt online from more beer and I got briess.  Normally I get my malt from my homebrew shop. Don't know what malt they carry.  So it was possibly a completely different malt.   Wonder if that could possibly be it.    They hydrometer sample tasted fine, but it was still kind of yeasty and I actually don't know what a super super dry IPA will taste like. 

[HoosierBrew]

John, I gather from your two posts that you are under the impression the FG was 1.008. It was 1.005.
Trapae: how's it taste, what's the body like? If its not too thin I wouldn't discount a measurement error.
If it tastes off infection is possible of course.
If its not infected and too thin I would try adding some munich or vienna to the base malt and/ or a touch more crystal and mash in mid 150's.
EDIT: for my personal taste I wouldn't add more crystal, just munich or vienna at 20%ish of a base blend.

You're right, Pete. It was early when I read it. I agree with your comments, too.

[denny]

Any idea what your pH was?  I have heard it can affect yeast attenuation towards the end.

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Not all that much.

[majorvices]

I have a hunch it is something in that conical fermentor that hasn't been cleaned well that is giving you a contamination or "super strain" issue. You say that you "consistently low final gravities" and that sounds like a problem is building up and now is really taking hold. Do you have ball valves? They can be a problem. Tri Clamps or threaded connections? Dirty gaskets?

You might check the final pH of the beer. Something under 3.8 could mean a bacterial infection.

[802Chris]

Was your OG measured or are you going off of estimate?

[trapae]

 So I bought a new hydrometer, calibrated it with distilled water to make sure it was  accurate.  Then I took another sample today, correct it for temperature, and it came out 1.008.  Still pretty dry, but not as bad as I thought. Next time I will probably mash couple points higher and see what that does. I clean my conical and all of my fittings and gaskets meticulously so hopefully I don't have an infection but will do an extra good thorough cleansing and sanitizing after this batch. Thanks for all of the advice.