Is my hydrometer off?

[Maheesh]

My +2 -2 hydrometer reads .996, my clinitest tablets say I have at least 10 g/liter sugar left. What does 10g/l equate to in terms of sg? Why are some ferments done at .996, some at .994, have even seen .992?

 

[winemaker81]

The answer to your last question is that every ferment is different. SG is the density of the liquid relative to distilled water. The ABV and solids in the wine affect the SG. Generally speaking, lighter wines with less "stuff" in them as well as wines with higher ABV will have a lower final SG.

 

[sour_grapes]

My +2 -2 hydrometer reads .996, my clinitest tablets say I have at least 10 g/liter sugar left. What does 10g/l equate to in terms of sg? Why are some ferments done at .996, some at .994, have even seen .992?

To answer your first question, Fermcalc tells me that 10 g of sugar added to 1 L of water gives a SG of 1.004. But your overall question seems to indicate that you are forgetting about alcohol. The amount of alcohol will vary the SG, as will the residual sugar.

 

[Maheesh]

How then do we know when the fermentation is completed?

 

[winemaker81]

How then do we know when the fermentation is completed?

Normally fermentation is considered complete when the SG <= 0.998 and has not changed for 3 days.

However, sometimes the ferment quits when the SG is a bit higher than that, for example I've had a few batches stop at 1.002 and never budge.

 

[Jim Welch]

@Maheesh when I get a new hydrometer I always “calibrate” it by measuring the SG of distilled water. For instance, a year or so ago I bought two low range hydrometers after breaking my old one. Both came to rest at 0.997 in distilled water from a freshly opened new container. Now I know to add 0.003 to any readings I take with either of these hydrometers.
If you haven’t yet I suggest you do this.

 

[winemanden]

What the Clinitest result is telling you, is the amount of sugar/glucose in the liquid being tested. It's not meant for winemaking, it will do the same in a sugar and water solution.
Trust your Hydrometer!
You only need Clinitest if you're making sparkling wine, or if you're diabetic.

 

[Hazelemere]

My +2 -2 hydrometer reads .996, my clinitest tablets say I have at least 10 g/liter sugar left. What does 10g/l equate to in terms of sg? Why are some ferments done at .996, some at .994, have even seen .992?

different levels of fruit extracts give you different residual SGs e.g. 0.994 has more extract than 0.992 if the ferment is done. e.g. a long slow ferment can give you more extract than a short fast ferment.

 

[Maheesh]

mystery solved, when I calibrated this hydrometer, it was reading .002 low…so I actually had .998, not .996. However, after reading these replies, after all these years relying on sg readings as being th final arbiter of fermentation completion, I decided the only thing to do is buy a
Densiometer. So I did.

 

[sour_grapes]

mystery solved, when I calibrated this hydrometer, it was reading .002 low…so I actually had .998, not .996. However, after reading these replies, after all these years relying on sg readings as being th final arbiter of fermentation completion, I decided the only thing to do is buy a
Densiometer. So I did.

Can you share a link to what you bought?

 

[Maheesh]

Anton paar easydens, find it at more wine.com

 

[Hazelemere]

To answer your first question, Fermcalc tells me that 10 g of sugar added to 1 L of water gives a SG of 1.004. But your overall question seems to indicate that you are forgetting about alcohol. The amount of alcohol will vary the SG, as will the residual sugar.

Water is SG 1.000 so 10 g sugar per litre raises SG to 1.004 so sugar free wine at 0.992 via sugar at 10 grams per litre gets you to SG 0.996. Sour Grapes answer is perfect.

 

[Rice_Guy]

How then do we know when the fermentation is completed?

Your basic definition of done is the yeast stop consuming sugar. It is finished if the reading doesn’t change. That said I have had high acid wine stop at 1.012, ,,, and after waiting nine months for a change I bottled without having to back sweeten.

 

[Obbnw]

If you are looking for accuracy down to .001 you need to account for temperature.

 

[David Violante]

Anton paar easydens, find it at more wine.com

That’s pretty darn cool.