Yeasty Hydometer sample

Thu Jan 03, 2013 9:06 pm

Hello all,
I just brewed up an IPA. OG was 1.085. I used WLP001, California Ale yeast with a 4L starter that was decanted off a week in advance. Beersmith predicted that my FG would be 1.015. I just took a measurement after a week. All bubbling has been done for a couple days now. My reading is 1.027. My hydrometer sample is very cloudy with yeast. How much, if any does all that yeast in the tube effect the gravity reading?

I am thinking that my yeast pooped out and I may need to pitch another small starter in there to finish it off, but maybe I don't. Could it just be all that yeast effecting my readings?

What do you guys think?

Thanks in advance,
:jnj
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Re: Yeasty Hydometer sample

Thu Jan 03, 2013 10:21 pm

What's your temp? Warm it and rouse those yeast and you may get a few more points off it.
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Re: Yeasty Hydometer sample

Fri Jan 04, 2013 12:50 am

Whenever I do a mid-ferment test where there's definitely going to be active yeast in solution, I cold-crash the test tube in the fridge. Get it below 40F for a little bit & you can get it to settle out. Allow it to come back up to testing temp slowly & naturally. I like to park it on top of the fermenter it came out of since that's going to be just slightly above 60 in most cases & will allow a nice gentle rise. And who doesn't like a nice gentle rise ;)
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Re: Yeasty Hydometer sample

Fri Jan 04, 2013 9:56 am

To answer your question, the yeast will not affect the gravity reading. Only things that dissolve into solution will change the specific gravity of your sample. A great analogy that AJ has used before is this:

Imagine a swimming pool filled with water. Throw a bunch of bowling balls into the pool. The bowling balls will raise the level of the water, but the water won't be any more dense.

Specific gravity is a measurement of the relative density of your liquid. Things, like yeast and hop particulate, that don't dissolve will not change the density.
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Re: Yeasty Hydometer sample

Fri Jan 04, 2013 10:39 am

Cody wrote:To answer your question, the yeast will not affect the gravity reading. Only things that dissolve into solution will change the specific gravity of your sample. A great analogy that AJ has used before is this:

Imagine a swimming pool filled with water. Throw a bunch of bowling balls into the pool. The bowling balls will raise the level of the water, but the water won't be any more dense.

Specific gravity is a measurement of the relative density of your liquid. Things, like yeast and hop particulate, that don't dissolve will not change the density.


Unless it is so deep the hydrometer is resting on it lol. But yes you are perfectly correct and that is a great analogy!
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Re: Yeasty Hydometer sample

Fri Jan 04, 2013 11:00 am

Ozwald wrote:And who doesn't like a nice gentle rise ;)

True, although the raging, rock hard ones that catch you by surprise have their place too...

Particulate matter only has and effect if it is so thick it is physically preventing the hydrometer from sinking... tried taking a grav reading on Oregon fruit puree, only went 1/3 of the way down the bulb.
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Re: Yeasty Hydometer sample

Fri Jan 04, 2013 1:20 pm

IF you have only let the beer ferment for one week, then you should continue to let it ferment for at least another week. check your gravity at the end of two weeks just to see where you are before making any decisions. If your yeast is still in suspension, there is a good chance it is still slowly fermenting away at the remaining sugars to reach your FG.

this of course depends on proper aeration levels, a low mash temp, use of any simple sugars, and fermentation temperatures (if possible, rouse your yeast and let your temps come up a bit to help the yeast finish out).
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Re: Yeasty Hydometer sample

Fri Jan 04, 2013 2:13 pm

brewinhard wrote:IF you have only let the beer ferment for one week, then you should continue to let it ferment for at least another week. check your gravity at the end of two weeks just to see where you are before making any decisions. If your yeast is still in suspension, there is a good chance it is still slowly fermenting away at the remaining sugars to reach your FG.

this of course depends on proper aeration levels, a low mash temp, use of any simple sugars, and fermentation temperatures (if possible, rouse your yeast and let your temps come up a bit to help the yeast finish out).

+1. Forget about it while the yeast does its thing. Too many testing samples could equal a pint! :shock:
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