When to stop secondary fermentation

[pilotdentist]

I am making a 5 gallon white wine batch purchased from a local winery and the directions said to add 2 lbs granulated sugar.

starting specific gravity was 1.085 and it’s at 0.990 now and I am still getting consistent bubbles (they are slowing slightly).

is it normal for specific gravity to get this low? I plan on letting the specific gravity continue dropping until the bubbling of the airlock is gone. Is it wrong clear now or should I definitely wait? Does it matter either way? Thanks!

 

[cmason1957]

Your SG probably isn't going to drop much lower. You may get bubbling every so often out your airlock, that is the CO2 coming out of the wine, not a sign of fermentation. You should wait until the SG stays the same for about 3 measurements in a row. Then you have to get the rest of CO2 out in order for it to clear. There are several ways for that to happen, in no particular order and probably not all: 1) wait, racking every so often, about every 3 to 6 months adding potassium metabisulphite at rackings; 2) apply vacuum, either by racking under vacuum or with a vacuum pump; 3) mechanically force it out with a drill mounted stirring device. My choice is a combination of 1 and 2 using the allinonewinepump, which is a vacuum pump and so much more.

BTW you don't stop the fermentation, it either stops due to no more sugar or the yeast die off due to high alcohol and secondary fermentation is misnomer, there is only one alcohol fermentation.

 

[winemaker81]

Most grape wines finish between 0.990 and 0.996. I've had 3 wines finish at 0.988, which is unusual but still normal. I concur with @cmason1957's advice, as will most of our frequent posters.

"Primary fermentation" is typically done in an open container (most of us put a towel over the top to keep stuff out) as the yeast needs O2 to replicate. This is also incorrectly referred to as "aerobic fermentation" as O2 is involved, but fermentation is the yeast eating sugar, and O2 is not required for that.

What is often called "secondary fermentation" occurs in a closed container as the yeast is done replicating and no longer needs O2, and it's referred to as "anaerobic fermentation", which is misleading, since fermentation is always anaerobic. The yeast is simply finishing its meal of sugar. Some folks press or first rack while there is activity, some let the wine ferment out and then press/rack. Either works fine.

@cmason1957 is correct about terminology -- but I'm don't expect we'll ever break everyone of the habit of using the incorrect terms. If we all know what is actually happening, I can accept the incorrect usage, although it's good that Craig and others ensure that newcomers understand what these things actually are.

 

[Scooter68]

If your reading is already .990 there is a 99% chance that the ferment is over. BUT just to make sure test some distilled water with your hydrometer. If it reads anything other than 1,.000 then your hydormeter is off and you will need to factor that error into your readings, or replace they hydrometer. IF the error is .001 or .002 I would not worry, but; you need to be aware of that.

.990 is considered a fully completed ferment in most cases.

 

[pilotdentist]

You guys should call Master Vintner and tell them to fix their terminology!

My wine is still fermenting. It is at 0.989 now so I am going to let it for longer before degassing, stabilizing, and clearing it.

 

[Scooter68]

Again verify that your hydrometer is reading correctly. (Test by measuring the SG reading of a test tube of Fresh Distilled water.)
Bubbling is not a sure sign of fermentation. It only indicates that some sort of gas is being released. CO2 gassing off normally occurs well after fermentation has stopped.

Also be sure that you are reading it correctly.

If this offends, I'm sorry but... folks forget or may not have learned the correct point to read:

 

[Raptor99]

"Primary fermentation" is typically done in an open container (most of us put a towel over the top to keep stuff out) as the yeast needs O2 to replicate. This is also incorrectly referred to as "aerobic fermentation" as O2 is involved, but fermentation is the yeast eating sugar, and O2 is not required for that.

This made me curious. I'm always interested in why things work, not only how they work. I found some resources to explain the point made by @winemaker81

1. All fermentation to produce ethanol is anaerobic (does not require oxygen): Difference Between Aerobic and Anaerobic Fermentation - Pediaa.Com

2. Yeast requires O2 to reproduce (so it is necessary in the growth phase): Guide to Macro Oxygenation and Fermentation | MoreWine

There's always more to learn!

 

[cmason1957]

You guys should call Master Vintner and tell them to fix their terminology!

My wine is still fermenting. It is at 0.989 now so I am going to let it for longer before degassing, stabilizing, and clearing it.

Yes, the kit instructions are guilty of staying to use secondary fermentation as moving the wine into a carboy. Fortunately, the last kit i made from RJSpagnals didn't use that term. I think they have realized what a wrong term it is. And yes it is my pet peeve, sorry.

 

[Riledup5]

Again verify that your hydrometer is reading correctly. (Test by measuring the SG reading of a test tube of Fresh Distilled water.)
Bubbling is not a sure sign of fermentation. It only indicates that some sort of gas is being released. CO2 gassing off normally occurs well after fermentation has stopped.

Also be sure that you are reading it correctly.

If this offends, I'm sorry but... folks forget or may not have learned the correct point to read:

View attachment 72448

Scooter, no offense taken and you are correct. Want your thoughts on this thought. As long as you are consistent in how the measuring is done (whether you measure at the top of the meniscus or at the true level), as long as you stay consistent in how you measure, then does it really matter? Keep in mind, I am a noob and am only using wine kits and therefore only measuring SG. Not sure if that would remain true if you are measuring other aspects when making country wine or if your starting point is actual grapes. Still much to learn.

 

[Scooter68]

Well, readings will be off by as much as about .002 if you read one way today and another way tomorrow IF the ferment has stopped completely. Consistency is important but we are not talking about something reaching a critical mass and "detonating"

Remember also the old issue of CO2 bubbles collecting on things. In the first days of paper straws you could put a straw in a soda and watch it rise up as much as a couple of inches as the CO2 collected on that straw. A hydrometer is much heavier of course but again those bubbles can affect a reading to some degree. Common method to overcome that is to Spin the hydrometer as you drop it into the testing tube and then read it as quickly as possible.
Does it matter that the reading is off by .002? NO. Nine times out of ten it doesn't matter but there is always that tenth time....
Unless you are looking to determine if a ferment has stopped or not, .002 difference means little to nothing. BUT for a slowly progressing ferment that is at 1.022 and you read it for 3 days as that same number and miss it by .002 THEN it might cause you to prematurely rack to a carboy and experience a foam fountain. Ferments often slow as they approach the end but the racking action from a bucket to a carboy can re-invigorate the yeast or just release a burst of CO2 either of which can produce the foam fountain.

 

[garymc]

You started at 1.085 and are down to .990. That's probably the end of the road. If you started at 1.100 or 1.110, you could expect to go below .990 if your yeast could tolerate that much alcohol. Starting with more sugar means you end with more alcohol if it completes, thus the specific gravity is less at the end. I ususally make higher than normal alcohol wines.

 

[Riledup5]

Well, readings will be off by as much as about .002 if you read one way today and another way tomorrow IF the ferment has stopped completely. Consistency is important but we are not talking about something reaching a critical mass and "detonating"

Remember also the old issue of CO2 bubbles collecting on things. In the first days of paper straws you could put a straw in a soda and watch it rise up as much as a couple of inches as the CO2 collected on that straw. A hydrometer is much heavier of course but again those bubbles can affect a reading to some degree. Common method to overcome that is to Spin the hydrometer as you drop it into the testing tube and then read it as quickly as possible.
Does it matter that the reading is off by .002? NO. Nine times out of ten it doesn't matter but there is always that tenth time....
Unless you are looking to determine if a ferment has stopped or not, .002 difference means little to nothing. BUT for a slowly progressing ferment that is at 1.022 and you read it for 3 days as that same number and miss it by .002 THEN if might cause you to prematurely rack to a carboy and experience a foam fountain. Ferments often slow as they approach the end but the racking action from a bucket to a carboy can re-invigorate the yeast or just release a burst of CO2 either of which can produce the foam fountain.

Thanks Scooter. I always appreciate your thoughts. And it's good to know my wine won't detonate! Well, I hope not anyway

 

[winemaker81]

As much as I prefer names and descriptions to be technically correct, I understand why kit instructions use the term "secondary fermentation". The audience for kit instructions is folks with no winemaking experience nor anyone experienced to help them. Calling it "secondary fermentation" clearly separates the process after the first racking. I can't think of a better thing to call it, so that a beginner will understand it.

Those of us who have been making wine for a while may forget just how complicated it may seem to the uninitiated. Reading the beginner's forum helps me keep that firmly in mind.

 

[Scooter68]

... Those of us who have been making wine for a while may forget just how complicated it may seem to the uninitiated. Reading the beginner's forum helps me keep that firmly in mind.

I agree and at the risk of crossing into politics I would suggest that those folks who do not have basic biology and chemistry in their schooling, are always going to find wine making hard to understand. When schools trimmed those subjects off the list of mandatory classes we lost a lot of what use to be "Common Knowledge" That and the terminology we are saddled with like "Secondary Fermentation," "Raising the Acidity" vs "Lowering the pH" all make it a bit tougher to understand what is really a natural phenomena that we are simply working with in a controlled way.