Under attenuation & water treatment

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kev

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I've never really used water treatments before until my last few brews and have been adding a heaped teaspoon of gypsum into my mash.

Everything seems ok but a couple of brews haven't attenuated as much as I expected and the only thing I can think of is the gypsum.

All the brews have had either used yeast from a previous batch or I've used a 2 litre starter. In addition, I've used yeast nutrients, etc and oxygenated the wort.

Anyone else have this issue??

K
 
Just to add to the above, today I bottled my Stone Ruination clone and it finished at 1020 and I wanted 1015.

I used 007 (Dry English Ale) and punching the numbers into beer smith I'm getting 67% attenuation and white labs site states this yeast operates at 70-80%.

I'm not miles off but it's not where I want to be.

K
 
Interesting article here :

http://byo.com/recipes-tag/item/1338-rx ... g-problems

And specifically ..........

Under-attenuation occurs when fermentation is not completed; this may be a yeast problem or it may be a brewer problem. Yeast that fails to complete fermentation may have been affected by residual sanitizer still in solution due to poor rinsing, by lack of dissolved oxygen in the wort, by cold temperatures, by extremely high or low pH levels in the wort, or the yeast itself may have been old and fatigued and incapable of multiplying in numbers great enough to complete fermentation. Also, certain liquid yeast strains are known to have low attenuation rates and may have to be roused during the fermentation cycle — consult the manufacturer’s data regarding yeast attenuation.
 
How high is the calcium in your tap water? Be aware that yeast flocculation with some strains can be premature when the calcium content is high. For most ale strains, around 50 ppm calcium is enough for adequate flocculation. Lager strains need even less calcium.

Hopefully you are also adjusting your mash pH as necessary since a high pH can reduce the fermentability of the wort.
 


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