Does airlock bubbling after FG reached means ferm still happening?

[Cro Magnon]

I've left a wheat ale in the fermenter for about two weeks now. About one week in the bubbling had long since stopped and I took a sample for the FG reading. However after I closed it back up, very slow bubbling has started again and has continued for several days.....like one bubble every twenty minutes or so. I thought I'd bottle today but the odd bubble is still happening....does this mean fermentation hasn't completed? Should I wait? What if it goes on bubbling for decades?

 

[Cro Magnon]

Should mention that I brew very small batches and two gravity readings have already cost me 500ml so I'd like not to take another one...what's a safe bet as to assume when fermentation is done?

 

[Rob2010SS]

No, airlock activity is never a sign of fermentation. Stable gravity readings are the only way to verify you're done. Airlocks can bubble all the time. As pressures outside of the fermenter or inside of the fermenter adjust, the airlock can bubble. One bubble every 20 min is not a sign of active ferm. Off the cuff, I'd say it's done and you're safe to bottle.

You said you took 2 gravity readings - what were they?

 

[Cro Magnon]

No, airlock activity is never a sign of fermentation. Stable gravity readings are the only way to verify you're done. Airlocks can bubble all the time. As pressures outside of the fermenter or inside of the fermenter adjust, the airlock can bubble. One bubble every 20 min is not a sign of active ferm. Off the cuff, I'd say it's done and you're safe to bottle.

You said you took 2 gravity readings - what were they?

oh great thanks! Really what I needed to hear cos I'm in a big hurry to bottle this one. Much appreciated!

 

[doug293cz]

If you don't want to use large samples to check SG, you can use a refractometer, which only takes a few drops. The refract will not read accurately in the presence of alcohol, but if the readings are stable at least two days apart, then fermentation is complete. There are calculators that will give you a reasonable estimate of the current SG if you know the OG, but most accurate if you really want to know the FG is a hydrometer.

You could also use a Tilt hydrometer (or it's DIY equivalent) to monitor SG without having to sample or even open the fermenter. The data is a little noisy, but if you watch the trends, you can tell when fermentation has stopped.

Brew on

 

[Cro Magnon]

If you don't want to use large samples to check SG, you can use a refractometer, which only takes a few drops. The refract will not read accurately in the presence of alcohol, but if the readings are stable at least two days apart, then fermentation is complete. There are calculators that will give you a reasonable estimate of the current SG if you know the OG, but most accurate if you really want to know the FG is a hydrometer.

You could also use a Tilt hydrometer (or it's DIY equivalent) to monitor SG without having to sample or even open the fermenter. The data is a little noisy, but if you watch the trends, you can tell when fermentation has stopped.

Brew on

Hey thanks for your reply! I knowww I really really wanted to get a refracto. I found out just after I got a hydrometer Interesting though that you say that hydrometers still give the most accurate readings. And unfortunately don't get tilt hydrometers where I live . I was wondering though, if I sanitize the sample test tube, and the hydrometer, can't I return the sample to the fermenter after testing?

 

[doug293cz]

Hey thanks for your reply! I knowww I really really wanted to get a refracto. I found out just after I got a hydrometer Interesting though that you say that hydrometers still give the most accurate readings. And unfortunately don't get tilt hydrometers where I live . I was wondering though, if I sanitize the sample test tube, and the hydrometer, can't I return the sample to the fermenter after testing?

Yes, you can return the sample to the fermenter. However, even with good sanitization, you still increase your risk of infection. You also will oxidize the wort a bit with the handling. How big an adverse effect the oxidation will have will depend on the style of beer. Hoppy beers are some of the most sensitive to oxidative degradation, with NEIPA's being extremely sensitive to oxidation.

Brew on

 

[Cro Magnon]

Yes, you can return the sample to the fermenter. However, even with good sanitization, you still increase your risk of infection. You also will oxidize the wort a bit with the handling. How big an adverse effect the oxidation will have will depend on the style of beer. Hoppy beers are some of the most sensitive to oxidative degradation, with NEIPA's being extremely sensitive to oxidation.

Brew on

Ahhh so seems like just too much of a risk then considering the amount off work. I guess I'll look up into what styles are less sensitive to oxidation and maybe experiment with those. And sorry I missed your question asking about my gravity readings. Well my OG was 1.036 and FG was 1.005 but I made two blunders taking the OG - sample wasn't cooled to the right temperature and 2 - took the sample AFTER adding the top up water.... I know, I know...amateur errors but I am an amateur!

 

[doug293cz]

Ahhh so seems like just too much of a risk then considering the amount off work. I guess I'll look up into what styles are less sensitive to oxidation and maybe experiment with those. And sorry I missed your question asking about my gravity readings. Well my OG was 1.036 and FG was 1.005 but I made two blunders taking the OG - sample wasn't cooled to the right temperature and 2 - took the sample AFTER adding the top up water.... I know, I know...amateur errors but I am an amateur!

You want to take your OG reading after adding top up water, but you need to stir very aggressively in order to not have stratification of the high density and low density wort. Lack of sufficient stirring is the most common cause of OG readings that don't match targets (when doing extract brews.)

Brew on

 

[IVeladRiENtArtHeMaNaRMiTh]

Ahhh so seems like just too much of a risk then considering the amount off work. I guess I'll look up into what styles are less sensitive to oxidation and maybe experiment with those. And sorry I missed your question asking about my gravity readings. Well my OG was 1.036 and FG was 1.005 but I made two blunders taking the OG - sample wasn't cooled to the right temperature and 2 - took the sample AFTER adding the top up water.... I know, I know...amateur errors but I am an amateur!

I'm a n00b myself, but it seems that if you add in top-up water, and then check the gravity -- that isn't an error. The sugar in solution will be reduced due to the top up water.

My only concern is if you measured the water on the top and not the total gravity, since you'd have to stir it, which would aerate it

 

[doug293cz]

I'm a n00b myself, but it seems that if you add in top-up water, and then check the gravity -- that isn't an error. The sugar in solution will be reduced due to the top up water.

My only concern is if you measured the water on the top and not the total gravity, since you'd have to stir it, which would aerate it

Aeration is actually desirable immediately before or after yeast pitching. But once fermentation has started, aeration should be avoided.

Brew on

 

[Cro Magnon]

You want to take your OG reading after adding top up water, but you need to stir very aggressively in order to not have stratification of the high density and low density wort. Lack of sufficient stirring is the most common cause of OG readings that don't match targets (when doing extract brews.)

Brew on

Woah...you almost lost me at stratification but ok I get it now! Wow I didn't know I was actually doing the right thing ( aside from the stirring) K so that's just one extra stirring spoon to sanitize...not bad!

 

[Cro Magnon]

I'm a n00b myself, but it seems that if you add in top-up water, and then check the gravity -- that isn't an error. The sugar in solution will be reduced due to the top up water.

My only concern is if you measured the water on the top and not the total gravity, since you'd have to stir it, which would aerate it

Thanks! This helped me to understand what doug was referring to with stratification. Like I said, I'm surprised I was doing the right thing vis-a-vis taking OG reading after the top up!

 

[jimyoung]

yeah, as everyone else said. Basically CO2 dissolved in the liquid can come out for ages. especially if it starts to warm up a little.

As for refractometer vs hydrometer, I bought a refractometer years ago and absolutely love it. There are several concerns that people raise.. the biggest ones are:
1) you need to find out the conversion factor, since it's probably calibrated for sucrose water, not wort
2) alcohol throws off the readings.

Over the years many times I have done calibrations and comparisons between my refractometer and hydrometer..
1) they always give the /exact/ same reading
2) if you know the OG, then this calculator gives me /exact/ same reading as my hydrometer

The only hiccup I've seen is that if you use the refractometer during mash / boil, make sure you cool your sample down. a hot sample throws it right off

 

[Cro Magnon]

yeah, as everyone else said. Basically CO2 dissolved in the liquid can come out for ages. especially if it starts to warm up a little.

As for refractometer vs hydrometer, I bought a refractometer years ago and absolutely love it. There are several concerns that people raise.. the biggest ones are:
1) you need to find out the conversion factor, since it's probably calibrated for sucrose water, not wort
2) alcohol throws off the readings.

Over the years many times I have done calibrations and comparisons between my refractometer and hydrometer..
1) they always give the /exact/ same reading
2) if you know the OG, then this calculator gives me /exact/ same reading as my hydrometer

The only hiccup I've seen is that if you use the refractometer during mash / boil, make sure you cool your sample down. a hot sample throws it right off

Thanks that's a lot of great info! I'm now seriously considering a refracto. What is the conversion factor and how do you find it out for your particular refracto? Also are there different kinds of refractometers like there are so many different kinds of hydrometers? Which one should I get for brewing?

 

[doug293cz]

Thanks that's a lot of great info! I'm now seriously considering a refracto. What is the conversion factor and how do you find it out for your particular refracto? Also are there different kinds of refractometers like there are so many different kinds of hydrometers? Which one should I get for brewing?

I prefer the refracts that have a single Brix scale. Lots of refracts are dual scale with both Brix and SG, but unfortunately many of the SG scales were not converted correctly from Brix, so the SG scale is worse than useless. There are refracts made for things other than sugar solutions (e.g. for salt solutions) - you do not want one of these.

Brew on

 

[jimyoung]

I always note both the SG and BRIX noted on mine. All my converters always tell me they're the same thing, so I guess mine is fine that way.

A good way to check the conversion factor for yours, is to:
- calibrate your refractometer with your base tap water (some use distilled water). This takes like 5 seconds and you should do it every time you use it anyway
- take a reading of some wort you have made.
- with the exact same wort, take a reading with a hydrometer

if it's different, you need to calculate your conversion factor (e.g., as a percentage) so that you can correct. Whenever I've checked mine, I've gotten the same reading.

I found my old email. I bought this one in 2015
https://www.amazon.ca/dp/B00DRTV7EY/ref=pe_386430_30332290_TE_3p_dp_1

 

[ncbrewer]

To get OG with an extract batch, you can easily figure it from the extract ppg - it will be right on. Gravity points from specialty grains can be figured from tables. They won't be exact, but very close. I haven't taken an OG sample on an extract batch in many years.

 

[Cro Magnon]

I always note both the SG and BRIX noted on mine. All my converters always tell me they're the same thing, so I guess mine is fine that way.

A good way to check the conversion factor for yours, is to:
- calibrate your refractometer with your base tap water (some use distilled water). This takes like 5 seconds and you should do it every time you use it anyway
- take a reading of some wort you have made.
- with the exact same wort, take a reading with a hydrometer

if it's different, you need to calculate your conversion factor (e.g., as a percentage) so that you can correct. Whenever I've checked mine, I've gotten the same reading.

I found my old email. I bought this one in 2015
https://www.amazon.ca/dp/B00DRTV7EY/ref=pe_386430_30332290_TE_3p_dp_1

Great! Gonna try this...thanks!