How do I know when fermentation is complete when the "consistent FG" rule isn't working?

[Evan La Marr]

How do I know when fermentation is complete?

I’m on my second ever brew, both of which have been Saisons, and I’m having trouble understanding when fermentation is complete.

I thought it would be done whenever it’s not bubbling through the airlock anymore, but the guy at my LHBS said not to worry about that, and that the general rule of thumb is that when you take the same gravity reading over 2 to 3 days and it’s near 1.010, then it’s probably done.

I ignored the CO2 bubbles and, after about a week, measured a FG of 1.012 over two days, so I racked, primed and bottled it. Carbonation only took TWO DAYS, and the beer was as green as the rainforest - all estery and weird-tasting. It tasted kinda like salty bananas. I let it settle for another week and a half, and it had come into it's own, and was actually pretty good. Like Leffe, but drier.

Anyways, I've had my second Saison in the fermenter for a week, and the airlock went from bubbling ever 1.5 seconds during the first three days to bubbling every 40 seconds now.

Given my past experience with the "same FG over a few days" rule not working, how do I know when fermentation is complete?

Thanks for your help,

Your not-so-local noob

 

[kh54s10]

Your same FG reading is working. That is the ONLY way to be sure fermentation is finished.

Your beer might taste "green" because you didn't give it enough time. I go 2 weeks always, sometimes longer. Bottle conditioning takes longer than a couple of days. In general at 2 weeks some might have good carbonation and some may not. In my experience ALL of my bottled beers have tasted better at 3 weeks conditioning or longer.

But I have heard that some Saison yeasts take a long time to fully ferment so, depending on what yeast, I would take a first reading at about 2-3 weeks then wait another 2 weeks to take another. Make sure the gravity is not still dropping or you risk over carbonation and possible bottle bombs.

 

[Rob2010SS]

How do I know when fermentation is complete?

I’m on my second ever brew, both of which have been Saisons, and I’m having trouble understanding when fermentation is complete.

I thought it would be done whenever it’s not bubbling through the airlock anymore, but the guy at my LHBS said not to worry about that, and that the general rule of thumb is that when you take the same gravity reading over 2 to 3 days and it’s near 1.010, then it’s probably done.

I ignored the CO2 bubbles and, after about a week, measured a FG of 1.012 over two days, so I racked, primed and bottled it. Carbonation only took TWO DAYS, and the beer was as green as the rainforest - all estery and weird-tasting. It tasted kinda like salty bananas. I let it settle for another week and a half, and it had come into it's own, and was actually pretty good. Like Leffe, but drier.

Anyways, I've had my second Saison in the fermenter for a week, and the airlock went from bubbling ever 1.5 seconds during the first three days to bubbling every 40 seconds now.

Given my past experience with the "same FG over a few days" rule not working, how do I know when fermentation is complete?

Thanks for your help,

Your not-so-local noob

I wouldn't say it's not working... if FG is the same after multiple days, you're done. I'd say check once and then check again in 2 days. If it hasn't moved, you're done.

There's no way you're beer was carbonated after two days. It takes me that long in a keg at 30psi and bottles can't hold that kind of pressure. Although it's a smaller volume so not 100%positive. My guess is that after 2 days when you tried it the yeast are still doing their thing. Any co2 in there probably caused some foam but it wasn't carbonated. The activity of the active yeast was probably the weird flavors.

 

[mongoose33]

I've had final gravities ranging from 1.015 to 1.008, depending on various conditions of recipe and mashing. If you have a lot of nonfermentable sugars in the wort, it's not going to finish as low. You can control that, if you're mashing, with mash temp; low produces more fermentable sugars (and a lower FG), high produces more fermentable sugars, and a higher FG.

The key, as others have said, is stability, but you do need to have an idea around where you expect to end up.

 

[beernutz]

Depending on the type of yeast used, Saisons typically have a lower final gravity than where you're at. The BJCP FG range is 1.002 to 1.008 and most brewers I know try to get to the lower half of that. You might try upping the fermentation temp slightly to get some additional attenuation.

Give the yeast a chance to work as they are still cleaning up the byproducts of fermentation even after airlock activity ends. One of the hardest things new brewers have to learn is patience imo.

How do I know when fermentation is complete?

I’m on my second ever brew, both of which have been Saisons, and I’m having trouble understanding when fermentation is complete.

I thought it would be done whenever it’s not bubbling through the airlock anymore, but the guy at my LHBS said not to worry about that, and that the general rule of thumb is that when you take the same gravity reading over 2 to 3 days and it’s near 1.010, then it’s probably done.

I ignored the CO2 bubbles and, after about a week, measured a FG of 1.012 over two days, so I racked, primed and bottled it. Carbonation only took TWO DAYS, and the beer was as green as the rainforest - all estery and weird-tasting. It tasted kinda like salty bananas. I let it settle for another week and a half, and it had come into it's own, and was actually pretty good. Like Leffe, but drier.

Anyways, I've had my second Saison in the fermenter for a week, and the airlock went from bubbling ever 1.5 seconds during the first three days to bubbling every 40 seconds now.

Given my past experience with the "same FG over a few days" rule not working, how do I know when fermentation is complete?

Thanks for your help,

Your not-so-local noob

 

[Evan La Marr]

I wouldn't say it's not working... if FG is the same after multiple days, you're done. I'd say check once and then check again in 2 days. If it hasn't moved, you're done.

There's no way you're beer was carbonated after two days. It takes me that long in a keg at 30psi and bottles can't hold that kind of pressure. Although it's a smaller volume so not 100%positive. My guess is that after 2 days when you tried it the yeast are still doing their thing. Any co2 in there probably caused some foam but it wasn't carbonated. The activity of the active yeast was probably the weird flavors.

I'm not freakin' lying! lol It was 100% carbonated in two days! I know what beer is supposed to be like - I've certainly drunk years of it. No bombs either. *knock on wood* Of course the yeast wasn't finished cuz it tasted like crap, but I can 100% confirm that it was carbonated after two days. Thank God I didn't have any bottle bombs.

 

[mongoose33]

I'm not freakin' lying! lol It was 100% carbonated in two days! I know what beer is supposed to be like - I've certainly drunk years of it. No bombs either. *knock on wood* Of course the yeast wasn't finished cuz it tasted like crap, but I can 100% confirm that it was carbonated after two days. Thank God I didn't have any bottle bombs.

It's possible it was carbonated if there was a lot of unfermented sugar remaining and a lot of yeast. I use a stainless conical and toward the end of fermentation I seal it up so the last points of gravity carbonate the beer--much like how a bottle conditions.

Someone--can't recall who--likened yeast producing CO2 in the beer as billions of tiny carb stones all working to get CO2 into solution. If it's a sealed container, it carbs fast. But that's with active fermentation ongoing. Normally with bottle conditioning the yeast still in suspension are relatively few in number, and mostly dormant. They are awakened by the addition of bottling sugar, and because there are relatively few in number, the process of carbing beer in the bottle takes 2-3 weeks.

But if you transferred actively fermenting beer into the bottles, yeah, I can imagine it's fully carbed in just two days. Just be glad you didn't have bottle bombs if that's what has happened.

 

[Rob2010SS]

I'm not freakin' lying! lol It was 100% carbonated in two days! I know what beer is supposed to be like - I've certainly drunk years of it. No bombs either. *knock on wood* Of course the yeast wasn't finished cuz it tasted like crap, but I can 100% confirm that it was carbonated after two days. Thank God I didn't have any bottle bombs.

Haha i wasn't calling you a liar. I just didn't think it could carb that fast even with active fermentation going on. Sorry if it came off that way.

 

[RM-MN]

There are two related things that we call carbonation. My latest bottled beer was carbonated in 2 days but there was almost no heading on it. That's normal, the carbonation with bottled beer and corn sugar happens really quick, even with beer that has been in the fermenter for a couple weeks or more. Waiting a couple weeks more will get the heading started and at 3 weeks the heading will be quite good and the flavor of the beer will have changed if there is any Crystal or darker malts with the darker beers taking longer, much longer, to mature.

 

[Calder]

Unless you are trying to get hoppy goodness in the glass as quickly as possible, there is no need to rush the beer. My Belgians are usually 5 weeks before being bottled, sometimes more. Waiting a while will give you clearer beer into the bottle, and less sediment.

Some of the Belgian yeasts like to take a rest part way through, so taking your time with it allows it to properly finish. 1.012 seems high for a Belgian to finish at, but it does depend on the recipe and the yeast.

 

[GPP33]

FG tells you when the the yeast is done eating all of the sugar it’s capable of consuming, not when the beer is ready for you to consume. The latter is dependent on style and off flavors produced which need to clear. I’ve found 2-3 weeks works well for most styles.

 

[Smellyglove]

TS is mentioning saisons. Which yeasts were used? If it was for instance 565 this bugger often just takes a siesta, then continues to work. If the SG measurements were done during the siesta, he would read a "stable" SG, but it might have woken up again and started to chew along in the bottles.

Another thing with saisons is a lot of those yeasts, especially the dry ones contains the diastaticus gene, which excretes an enzyme which breaks down longer chained sugars to shorter ones, they will ferment until there's almost just water/alcohol left in the beer.

Some of the saison strains need about 3-4 weeks before you can read an actual stable SG. They can be finicky.

I don't doubt that it was carbonated after two days, I'm having carbonated hefes after tree days if it's been warm enough, but it doesn't mean it was "fully" carbonated in regards to the amount of potential fermentable extract in the bottles.

 

[Evan La Marr]

TS is mentioning saisons. Which yeasts were used?...

the first batch was SafAle BE-134, which was quite a rager, and this second batch was Lallemand Belle Saison, which seems to be less active than the BE-134 judging by the amount of bubbling in the airlock.

1st batch:
OG: 1.056
FG: 1.012 (premature measurement as apparent in the original post)

2nd batch:
OG: 1.062 (including steeping 8 oz. of Caramel-20 in 5 gal. of water)
FG: ?

 

[Smellyglove]

the first batch was SafAle BE-134, which was quite a rager, and this second batch was Lallemand Belle Saison, which seems to be less active than the BE-134 judging by the amount of bubbling in the airlock.

1st batch:
OG: 1.056
FG: 1.012 (premature measurement as apparent in the original post)

2nd batch:
OG: 1.062 (including steeping 8 oz. of Caramel-20 in 5 gal. of water)
FG: ?

Both of them are diastaticus at least. You're not the first one having this problem with diastaticus.. If not left until it's usually bone dry, it will continue to chew in the bottle