Porters and Stouts are finishing too high.

My brew partner and I are experiencing a consistent trend with porters and stouts finishing around 1.020 and not drying out like previous batches.

Our temp control and aeration methods could be improved, but all the pilsners and ales are finishing as expected. So ....

Could this be pH/water related? Do certain dark malts affect the pH to level where it inhibits complete fermentation? Something else?

We are just starting to understand water chemistry adjustments and currently do not alter our brew water in any way. The water we use is well water in central VT.

We're stumped. We'd love to hear some advice and suggestions please ...

Thanks.

Joe

Are you doing AG or PM?

All Grain.

What temps are you mashing at?

Out of habit for years I've added gypsum to all dark ales and have never had a problem. It won't hurt to try it.

ChshreCat said:

What temps are you mashing at?

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We generally hit temps from 148 F to 152 F. Nothing real extreme.

recipe info would help....if you've got a lot of crystal malt, for instance, that could be part of the problem.

HSM said:

Out of habit for years I've added gypsum to all dark ales and have never had a problem. It won't hurt to try it.

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most of the time this shouldn't be necessary...gypsum will drop your pH, same as lots of dark malts.

if you've got really high carbonate water, it's probably not going to hurt, but if you've got soft water, you mash pH will probably be lower than you want with dark ales + gypsum additions.

Are you comparing previous AG stouts and porters to current ones or porters and stouts to pales and pilsners?

BuzzCraft said:

recipe info would help....if you've got a lot of crystal malt, for instance, that could be part of the problem.

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Some recipe info on the porter...

Pale malt 8 #
Munich 1#
Crystal 60 1#
Black Patent .5#

This doesn't qualify for "a lot" of crystal, right?

david_42 said:

Are you comparing previous AG stouts and porters to current ones or porters and stouts to pales and pilsners?

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A little of both, I suppose. We had better attenuation from the dark ales over the summer ... that's why it's a bit of a mystery. Maybe try fermenting closer to 68 -70F would help?

With the same Am. Ale yeast used on dark or light ales, the percent attenuation is higher for light ales, upwards to 10 percent higher. Is that to be expected?

If your water doesn't have a high enough alkalinity buffer, the pH could be getting too low, not allowing the the alpha and beta amylase enzymes to work on the starches in the grain. Try using 5.2 on your next stout and see how that turns out.

gophilliesgo said:

Maybe try fermenting closer to 68 -70F would help?

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Are you not fermenting at that temp now?

I've had Am Ale yeast struggle much below 65 but it is very happy at 67 and above. So yes, you might trying increasing your fermentation temp if you are much below that. You might also try ramping your temp 4-5*F the last 1/3 or 1/4 of fermentation to keep the yeast active a little longer. It won't create any off flavors.

If you can't get it worked out by increasing the fermentation temperature...

I oxygenate with an oxygen wand from Williams Brewing. I've not done a side by side test to know if this is helping but many believe it does. Also how old is the yeast? If it is old you might want to do a starter.

Good luck!

JT

mightynintendo said:

Are you not fermenting at that temp now?

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No, somewhere around 63-64F. Trying to keep a constant temp in a wood heated cabin in the VT winter is quite a challenge. But it can be done.

mightynintendo said:

If your water doesn't have a high enough alkalinity buffer, the pH could be getting too low, not allowing the the alpha and beta amylase enzymes to work on the starches in the grain. Try using 5.2 on your next stout and see how that turns out.

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Awesome. I've never heard of this product and I look forward to trying it. Sounds like it would be appropriate for all styles, right?

Alkalinity buffer? I'm going to dive into more water research. Can you recommend a resource to get myself educated as a starting point.

The water in our area to be around 6.6 pH and tends to lean a bit on the "hard" end of the spectrum.

Thanks for all the pointers so far guys, this is great.

gophilliesgo said:

No, somewhere around 63-64F. Trying to keep a constant temp in a wood heated cabin in the VT winter is quite a challenge. But it can be done.

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Ok well I would start here but I doubt this is the entire reason your fermentations are incomplete since you've had success with other beers. Get that temp up to 68-70! Those yeasties are a picky group, and if they're too cold they simply go on strike. You may find that raising the temp on a 63-64F batch that seems to have stopped will re-activate the fermentation. Try putting your fermenter on top of an electric blanket but watch it carefully for a day to make sure you don't get it TOO warm. Of course many american ale yeasts will ferment perfectly fine in the lower 60's, so age and yeast strain may have a lot to do with this as well.

gophilliesgo said:

Awesome. I've never heard of this product and I look forward to trying it. Sounds like it would be appropriate for all styles, right?

Alkalinity buffer? I'm going to dive into more water research. Can you recommend a resource to get myself educated as a starting point.

The water in our area to be around 6.6 pH and tends to lean a bit on the "hard" end of the spectrum.

Thanks for all the pointers so far guys, this is great.

Click to expand...

Alkalinity buffer is a measure of how resistant your water is to a change in pH towards the more acidic. Read through these pages: http://www.howtobrew.com/section3/chapter15.html

Hard water is generally good for most brewing except for pilsner lagers, so you're lucky there. Kansas City softens their water so I have to add calcium chloride and baking soda (sodium bicarbonate). The baking soda is what buffers the alkalinity and keeps your wort from becoming too acidic when mashing darker grains, so this may be what you end up using.

Another useful online tool to determine what mineral additions you may need (if any) is here: http://www.brewersfriend.com/water-chemistry/