Hydrometer readings

[SLiM_Pickins]

Hi guys, I'm a new brewer. Started a batch of
Cooper's Australian lager. it's the seventh day of the primary, my og was 1.050 and now it's 1.002 . Its not done fermenting yet, and I had some yeast foam overflow at the beginning. I calculated that would be an estimated 6.30℅, is that correct, and how much stronger could it end up by the time it's done? By the way, I'm drinking Busch ice right now and my homebrew already tastes stronger lol.

 

[Subdivisions]

Don't know if you looked at your other post but are you sure it's 1.002 and not 1.020?? It's really hard to get a beer that low unless it is mostly sugar.

 

[SLiM_Pickins]

Accidentally added 1.2 kg of dextrose instead of just 1kg, this was my first test after a week

 

[SLiM_Pickins]

Love Rush by the way

 

[Hex23]

Its not done fermenting yet

What is this based on? Is the gravity still changing, or are you seeing the air-lock bubble?

 

[SLiM_Pickins]

Airlock is still bubbling slightly, but all of the yeast fell out of suspension

 

[Hex23]

Airlock is still bubbling slightly, but all of the yeast fell out of suspension

The airlock activity is probably just continued off-gassing of CO2. After that many days, it's likely the main fermentation is over. I second Subdivision's skepticism about 1.002. 1.050 -> 1.002 is about 96% attenuation, which is pretty unlikely, even with 1.2 kg sugar. By my calculations, that 1.2 kg sugar is contributing about 40% of the gravity, which is pretty high. But unless you have an infection or something, I don't think that's enough sugar to cause 96% AA. Does it taste fine?

 

[tim_s]

How do you know if you yeast is suspended or not? Clarity?

 

[Hello]

How do you know if you yeast is suspended or not? Clarity?

Yeast is likely always in suspension until you cold crash and/or add gelatin. The yeast I think he's referring to is the krausen layer that has since dropped.

OP, adding .2 kg more sugar than required would not really do much. I am wondering if your reading is 1.020 and not 1.002.

 

[tim_s]

My krausen layer dropped off today on day 3 of the fermentation, is this a sign of a problem?

 

[hvjackson]

Adding dextrose (or any other pure sugar) does not affect the final gravity at all, only the O.G. (and therefore the % attenuation). If your gravity really is 1.002 (unlikely), that might indicate contamination.

 

[SLiM_Pickins]

It tastes fine, a little fruity. It is a touch cloudy, but it looks pretty clean on the surface, just a thin layer of bubbles.

 

[hvjackson]

Did you recheck the FG reading? 1.002 is unusually low, and 1.020 is probably not done yet. I would not bottle / keg at 1.020 unless you get stable readings for several days (and even then I would probably try to kickstart fermentation a bit). Final gravity for a lager should be around 1.010, give or take.

 

[SLiM_Pickins]

Should I wait a bit longer: I just took a second reading, and it is still two hashmarks past the 1000 mark so I think it really is 1.002 My og was on the 1050 mark.

 

[tim_s]

Should I wait a bit longer: I just took a second reading, and it is still two hashmarks past the 1000 mark so I think it really is 1.002 My og was on the 1050 mark.

Could it be the temperature of the liquid? Most hydrometers are set for 60F.

 

[hartlesj]

The other thing to check is the Hydrometer itself. I learned this lesson the hard way. Use some distilled water and check the Hydrometer. I found mine was about +.008 off. If you look close, the markings on they Hydrometer are on a piece of paper that is placed in the glass tube. This paper can slide up or down inside the tube causing it to appear higher or lower than what it really is. It will move in shipping sometimes or in storage. I typically use tap water for a sanity check prior to each use unless I have a bottle of distilled water lying around then I will use that. I have read that you can move the paper by taping the hydrometer on the counter, but I haven't tried that as the glass looks awfully thin. I just write the difference down in my notes and add the difference to my SG reading.

Also the temp does matter. The markings are calibrated for a specific temp as one of the other posters pointed out. There should have been a chart that came with the Hydrometer that gives corrections for the temperature of the wort/beer that you are measuring. (if not you can find one on line) If the temp is higher than the calibrated temp, then the liquid will be thinner and the reading will indicate lower. So take the temp of the wort, consult the chart and add or subtract the number shown in the chart.

For a loose example...
Your reading. 1.002, if your temp is 68deg. vice 60, then add .003. Your hydrometer is off by .006 then add. You True FG is now 1.011.

 

[SLiM_Pickins]

Thank you so much! I have been measuring at 70 degrees and forgot to take that into account, and I will do a test with distilled water first to calibrate it.

 

[hvjackson]

I just took a second reading, and it is still two hashmarks past the 1000 mark so I think it really is 1.002

Nobody here can read your hydrometer for you, but mine has tick marks every 0.002, so two ticks would mean 1.004.

Also, as others have said, test your hydrometer in water to see if there is any error (tap or distilled doesn't matter). And make sure you're doing any temperature correction as necessary.

Another thing to check is to make sure you're reading from the bottom of the meniscus. If you read from the top of the meniscus you will get an artificially low reading. This site has lots of info on calibration, correctly reading, and temperature corrections: How to Take an Accurate Hydrometer Reading

 

[Hex23]

Adding dextrose (or any other pure sugar) does not affect the final gravity at all, only the O.G. (and therefore the % attenuation).

Please explain. This is counter to conventional wisdom. It's certainly not true if considering two beers of same OG, where one uses sugar adjuncts and the other all malted grains. Are you saying that simply adding sugars to an existing recipe will not cause it's FG to change (all else equal)?

 

[hvjackson]

Please explain. This is counter to conventional wisdom. It's certainly not true if considering two beers of same OG, where one uses sugar adjuncts and the other all malted grains. Are you saying that simply adding sugars to an existing recipe will not cause it's FG to change (all else equal)?

Your last sentence has it: simply adding (or changing) the amount of sugar in a recipe will not affect the final gravity. The OP was originally wondering if adding extra sugar was affecting the FG reading, and the answer is "no". Adding more sugar only raises the O.G., but since virtually all sugar is fermented out it won't affect the F.G.[1]

You're correct that by *substituting* gravity points from grain with points from sugar the FG can be changed. Typically this is done to make a "big" beer that is not too sweet. So if you have an 1.080 OG beer with a typical 75% attenuation [2], you will end up with a 1.020 FG beer (on the sweet side). If you instead removed 1/4 of the OG points and substituted with sugar, you would still start out at 1.080 but end up with at 1.015 FG beer (75% attenuation X 1.060).

[1] Strictly speaking the additional fermentation from adding sugar will lower the FG by a tiny amount since alcohol has a lower density than water, but that is independent of the sweet/dry issue and unless you are adding huge quantities of sugar it is a meaningless amount.

[2] Standard beer malts and yeast typically attenuate 75%; that is, the yeast will consume approximately 75% of the sugar and turn it into alcohol. Some factors like mash temperature and yeast health can help or hurt this number, but 75% is a good ballpark number. Sugar attenuates 100%, so all of it will be converted to alcohol. On the other hand, lactose is *not* fermentable, so adding lactose to a beer (e.g. a milk stout) will raise the OG *and* the FG, creating a sweeter beer with no change in alcohol content.

 

[SLiM_Pickins]

Okay, I checked my hydrometer with distilled water at 60 degrees and it's spot on, then I put some batch in my tube and cooled it to 60 degrees. Even made sure the hydrometer was the same temperature. I got a reading of 1.010, compared to 1.002 with just a 10 degree difference. So I figure my og was closer to 1.058 . It's already looking so much clearer than even yesterday, and it's looking darker and definitely starting to taste a lot nicer

 

[SLiM_Pickins]

Thanks for all your help guys, really appreciate it.

 

[SLiM_Pickins]

Was really worried that I lost too much yeast from a violent foamover also, but I think because I put 5 liters less water than I was supposed to, plus .2kg more dextrose that it needed, I might end up with a pretty strong tasting brew, but I enjoy experimenting, so it should be interesting

 

[Hex23]

So I figure my og was closer to 1.058.

You may not even need to guess on this one. If you're confident on the amount of extract and sugar you used and you know the volume at the end of the boil (or a topped up volume in the fermenter), then you can confidently calculate OG. In fact with extract, there's never any reason to measure OG.

BTW, there's no way you really got an 8 pt swing with 10 F difference in temperature. 10 F is closer to about 1 gravity point change. Probably some sort of measurement error, of which there are many varieties with a hydrometer.

 

[Hex23]

[1] Strictly speaking the additional fermentation from adding sugar will lower the FG by a tiny amount since alcohol has a lower density than water, but that is independent of the sweet/dry issue and unless you are adding huge quantities of sugar it is a meaningless amount.

This is along the lines of what I was thinking. Not sure what a "tiny amount" is - obviously depends on how much sugar you add. For the OP's situation, 40% of the gravity being dextrose means a good chance for a relatively low FG, e.g. 1.010

 

[hvjackson]

This is along the lines of what I was thinking. Not sure what a "tiny amount" is - obviously depends on how much sugar you add. For the OP's situation, 40% of the gravity being dextrose means a good chance for a relatively low FG, e.g. 1.010

OK, you got me. I just looked it up and it seems like for every 5 points of gravity added in sugar, the FG will be ~1 point lower (and the alcohol will go up by 1.5% pts). So if you add 0.010 gravity points in sugar to a recipe, the FG will be lowered by 0.002. This is a small amount, but maybe I overstated its smallness. I do maintain that adding sugar thusly will not affect the sweetness/dryness of the recipe; the FG lowering is caused simply by there being more alcohol, not the removal of residual sugar.