gravity readings

[breweRN]

I ferment on the 3rd floor so sometimes I take gravity readings and the sample sits there for a couple of days.

Here are my questions:

After about 24-48 hours, the gravity loses about 4 points. (goes from say 1.018-1.014) What is the reason for this? Which reading is more accurate?

 

[duboman]

One possibility is the change in temperature of your sample, try making an temperature reading and then adjusting for that, if the temp of your sample goes up say 5 -10 degrees your reading will be different.

 

[breweRN]

There may be a temp difference by, as you say, about 5-10 degrees. Would that change the gravity reading by 4 points!?

 

[JLem]

If the beer is not done fermenting, the yeast are continuing to do their thing and the gravity will continue to drop. Why are you keeping a hydrometer sample around for 24-48 hours?

 

[breweRN]

These readings are taken after the gravity of wort has been steady for well over a week. So fermenting should be more than done.

I keep it for a couple of days because I ferment on the 3rd floor and am too lazy at times to take it downstairs to dump it.

 

[Frankiesurf]

You don't dump samples, you drink them.

 

[oakbarn]

According to my BrewMath app A reading of 1.018 dropping to 1.014 cannot be a 10 degree difference at near room temps. The temp delta would need to be more, but any reading MUST be corrected for Temperature regardless. There will be a difference of the same sample at different temperatures, not just that great for a 10 degree delta.

 

[JLem]

These readings are taken after the gravity of wort has been steady for well over a week. So fermenting should be more than done.

I keep it for a couple of days because I ferment on the 3rd floor and am too lazy at times to take it downstairs to dump it.

It seems to me that if your sample reading is continuing to drop then your fermentation is not complete. Temperature changes may impact the reading, but 4 points is quite a drop. You'd need a pretty big temperature change to account for that.

 

[breweRN]

You don't dump samples, you drink them.

Ah, I know, I know I should. I hate to waste it, but I like my beer cold and carbonated. I don't just drink it because it's beer.

 

[breweRN]

It seems to me that if your sample reading is continuing to drop then your fermentation is not complete.

This sounds like the most reasonable explanation, however, this last time it has been in the fermenter for almost 3 weeks and the gravity ha been stable for almost 2 weeks.

If the rule of thumb is "it is time to bottle when fermentation is done, and fermentation is done with 3 consecutive readings (days) of the same gravity reading", than how am I supposed to now that my fermentation is done without letting the sample sit for 24 hours? (which apparently is not common practice)

 

[duboman]

I just threw the temp thing out there because he stated the gravity was stable, I also know that spring temps have been all over the place and the east coast got really warm. Being on the third floor I assumed the possibility that there was a large enough swing from top floor to bottom.

I know 5-10 degrees is not enough for a 4 pt drop but maybe the temp change was greater? Or... One day was 55 and the next was 75, as in Chicago we've had a few major swings like that over the past weeks.

 

[ajf]

If you are leaving the sample exposed to the air for several days, there is a good chance of getting a bacterial or wild yeast infection. That could easily cause a drop in gravity.

-a.

 

[JLem]

If you are leaving the sample exposed to the air for several days, there is a good chance of getting a bacterial or wild yeast infection. That could easily cause a drop in gravity.

-a.

I thought this might be an option as well, but the more I considered it, the more I doubted that you could a big enough population of bacteria or wild yeast going in just 2 days to drop it 4 points, especially considering the alcohol already on the beer.

 

[Frankiesurf]

Ah, I know, I know I should. I hate to waste it, but I like my beer cold and carbonated. I don't just drink it because it's beer.

It's research. I like to know how my beers are maturing and the process that they go through. You get a lot of different flavors from the early stages. It is kind of fun to try to figure out where they are coming from and how these flavors and aromas will develop into the finished product.

 

[breweRN]

I do sip it to get the taste, just can't drink the whole thing.