How do I lower my SG

I am not worthy...I will never buy old yeast again (unless it's on sale )

 

I don't perform measurements routinely using these tools currently - so I'm speaking from second hand experience only - but an experienced technician with good tools and an adequate dilution scheme should have a measurement uncertainty of around 5-15%.

 

Matt, thank you for your prompt response.
“ …an experienced technician with good tools and an adequate dilution scheme…” That is an important caveat. I do not think that a ‘regular’ homebrewer would meet those criteria.

“ …measurement uncertainty of around 5-15%.” Let’s just consider the 15% number right now for discussion purposes, would that be ± 15% or ±7.5%?

Cheers!

Jack

 

+/- 15%. but let's assume +/- 10% since that's at the midpoint of the guess I shared with you.

 

I am not a cell culture biologist, but a measurement which is only accurate to +/-10% by an experienced technician with good tools and an adequate dilution scheme does not sound like a very accurate scheme to me.

For example, let’s consider that a 1 month old smack pack of Wyeast is measured as having 110 billion viable yeast cells. That package could have anywhere between 121 and 99 billion yeast cells; a range of 22 billion yeast cells. This is comparable to the assumed die off value of 21 billion yeast cells used in the Mr. Malty yeast calculator (which I think is conservative/inaccurate based upon my discussions with Dr. Chris White).

If somebody where to conduct an analysis of yeast cell die off with this sort of measurement scheme/accuracy I am uncertain of its value.

Cheers!

 

I'm sorry - but this is logic is flawed.

If I tell you I measure 100 billion cells today, and then I tell you I measure 90 billion cells tomorrow - these are really the same numbers, because they fall within the realm of my experimental measurement. The measurement has told you effectively that there was no change.

If I tell you I measure 100 billion cells today, and I measure 80 billion cells tomorrow - or 20 billion cells in 3 months for example - this is a relevant experimental observation - because these two numbers are NOT within the same realm. There has been a definitive drop in cell count, that we can quantitate with the caveat that the data is +/- 10% accurate.

Pretend there was a probe - like a thermometer - that costs $10, and when you dipped it in your pack/vial/slurry/starter/fermenting beer, it gave you the cell count. The fact is, we would ALL do it - even with the 10% error - because it would likely improve the quality and consistency in our beer. How do I know this? Because the worlds biggest and best breweries do this all the time.

I recommend you read Yeast by Chris White. I will bet you a beer that the totality of that book is at least as valuable as that singular comment he made to you, and hopefully a whole lot more.

 

But huge compared to what? Reality? It might be reality. We don't know.

The basic question is... do refrigerated yeast die off in a percent of remaining cells per time period fashion? Or do dead cells in the environment, or nutrient depletion, or something else accelerate this into something that resembles an X Quantity per time period* fashion? Or is it somewhere in between, or much more complex? Without data, we're guessing. The former (percent of remaining cells per time period) feels more likely to me (as I think it does to you), but that's not evidence.

*X would be initially be a function of a percentage of a fresh 100% viable colony.

 

OP - bet you weren't expecting such a thorough answer, were ya

 

Measure with a micrometer.
Mark it with chalk.
Cut with a meat clever.

 

This thread was a good read, thanks Jack Vike & Matt

 

I was too. I fail to see how % difference is a valid metric, as it is based on the assumption that the numbers should be identical (which they clearly won't be). Interestingly the one thing I learned from this is the method I have always done percent difference based off (compare to the average, not the absolute difference) doesn't seem to be backed up, but then again I tend to use against multiple trials, not a pair...

Sigh. If the decrease is linear, we expect the percent difference to increase. If we assume it is a percentage left, then the difference remains constant. Which assumption is true? Can someone call Wyeast and ask please?

 

http://morebeer.com/products/oxygenation-partial-system.html
This is the one I purchased with the .5 micron stone

http://www.sears.com/craftsman-oxygen-cylinder-1.4oz/p-00954916000P
And you need one of these. They should have them at most hardware stores. They are usually $5-$10.

I run it 1 minute for normal gravity beers and 1:30-1:45 for higher gravity beers.

 

I think that you can get by with enough oxygen in your wort if you pour it roughly into your fermentation bucket so that bubbles are created when you do this. Trickling the beer from the kettle into the bucket will also give you good aeration, but protect the surroundings for excess splashing. I usually put my wort through a strainer to remove any dregs, and the strainer always does a good job aerating the beer too.

I can't comment on use an O2 system to aerate because I've never done that.

 

This BYO article entitled “Aerating wort: Techniques” may be helpful to you:http://byo.com/stories/item/1894-aerating-wort-techniques

Cheers!

 

I'd settle for the 1.018. Nominal for LME quite possible.