Is my hydrometer off?

Winemaking Talk - Winemaking Forum

Help Support Winemaking Talk - Winemaking Forum:

Maheesh

Senior Member
Joined
Sep 7, 2014
Messages
104
Reaction score
18
Location
Southern oregon
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

wine dabbler
Staff member
Super Moderator
Supporting Member
Joined
Nov 5, 2006
Messages
8,820
Reaction score
24,293
Location
Raleigh, NC, USA
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

Victim of the Invasion of the Avatar Snatchers
Supporting Member
Joined
Sep 19, 2013
Messages
14,527
Reaction score
17,351
Location
near Milwaukee
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.
 

winemaker81

wine dabbler
Staff member
Super Moderator
Supporting Member
Joined
Nov 5, 2006
Messages
8,820
Reaction score
24,293
Location
Raleigh, NC, USA
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

Supporting Members
Supporting Member
Joined
Feb 25, 2019
Messages
594
Reaction score
940
@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

Senior Member
Joined
Sep 30, 2009
Messages
988
Reaction score
2,819
Location
Banbury UK
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.
 
Last edited:

Hazelemere

Supporting Members
Supporting Member
Joined
Jun 25, 2022
Messages
416
Reaction score
463
Location
South Surrey, BC
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

Senior Member
Joined
Sep 7, 2014
Messages
104
Reaction score
18
Location
Southern oregon
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

Victim of the Invasion of the Avatar Snatchers
Supporting Member
Joined
Sep 19, 2013
Messages
14,527
Reaction score
17,351
Location
near Milwaukee
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?
 

Hazelemere

Supporting Members
Supporting Member
Joined
Jun 25, 2022
Messages
416
Reaction score
463
Location
South Surrey, BC
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.
 
Last edited:

Rice_Guy

Supporting Members
Supporting Member
Joined
Jan 29, 2014
Messages
3,772
Reaction score
5,299
Location
Food Industry - - Retired
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.
 
Top