Final gravity?

[Velnerj]

I'm brewing an amber ale with about 20% Crystal malts in the recipe (shooting for an Anderson Valley Boont homage). Using mangrove Jack's M15 Empire Ale Yeast. Mash was at 63C. Fermented for 7 days at 18C then 5 days at 20C followed by a three day cold crash at 5C.

Took a refractometer reading on the third day of 20C fermentation and read 8 brix. My OG was 1.062. This gave me a a reading correction of 1.013. Which I suspected was my FG. Let it ride two days, cold crashed and bottled.

At bottling I took a sample to measure with my hydrometer. 1.022!!! This sample was taken without priming sugar added... Refractomer reading is the same still (8 brix). I'm afraid now of bottle bombs :-(

What could account for this dramatic change in gravity readings?

A couple thoughts 1)hydro sample was cold perhaps around 10C 2) hydro sample was very cloudy and full of trub (but I thought that wouldn't matter)

Any thoughts on this conundrum? Should I be worried?

 

[Tobor_8thMan]

This is very strange. Is there a refractometer temp compensation? Strange to go from 1.013 up to 1.022 as this indicates there now more unfermented sugars than when the 1.013 sample was tested.

 

[foolsbrew]

Fermented for 7 days at 18C then 5 days at 20C followed by a three day cold crash at 5C.

12 days is enough for an ale yeast to finish fermentation, this leaves only two cases
a) stuck fermentation
b) bad hydrometer reading

The best thing with hydrometers are they are so simple and so easy to test. I'd first put the hydrometer in water and see if I get 1.0, faulty hydrometers are actually far from rare since we all usually buy the cheapest.
If the hydrometer is good, I trust the hydrometer over the refractometer any day.

Easiest way to test against a bad hydrometer reading is just dropping the hydrometer straight into your fermenter. I would just do that and that should tell you whether it's stuck or it was about the trub.

What could account for this dramatic change in gravity readings?

There is no change in gravity readings that we know of. Your refractometer reads the same, before and after. We don't know what the hydrometer read before, only that the number is different from the refractometer which isn't uncommon.

2) hydro sample was very cloudy and full of trub (but I thought that wouldn't matter)

It does matter. It just tells you the density of the liquid.

If you are taking the sample with a spigot from a bucket, and you had too much trub, you will suck some of the trub in your sample. It's easy to suck in enough to make a difference since you are drawing from near the trub.

If you have a wort sample with trub(like during mashing) and you wait a while before taking a sample, you will get a higher reading since a decent amount of it settled at the bottom. This doesn't matter here but it shows us the reading actually changes with trub.

If the hydrometer is in a cylinder that's not wide enough and the hydrometer is slightly touching one of the sides of the container, it will give a wrong reading. Spin it a little.

Hopefully it's one of these things and it's actually done.

1)hydro sample was cold perhaps around 10C

This matters too, but not nearly enough account for the difference.
https://www.brewersfriend.com/hydrometer-temp/

 

[Velnerj]

Wow I really appreciate the feedback.

I've tested my hydrometer in tap water and it read at or close to 1.000.

I've spun and bobbed my hydrometer to make sure it's not stuck.

I am using a spigot from a bucket and the sample was the first goop taken out of the fermenter. I still have the hydrometer in the sample waiting for it to, warm up settle down and see if fermentation starts up again.

The identical readings of the refractometer has me a bit at ease. But if it's a "stuck fermentation" could I still be getting bottle bombs or is it possible I've reached FG?

 

[Tobor_8thMan]

Is sample goop causing an invalid hydrometer reading?

Remember to adjust the hydrometer reading based on the hydrometer calibration value.

 

[foolsbrew]

The identical readings of the refractometer has me a bit at ease. But if it's a "stuck fermentation" could I still be getting bottle bombs or is it possible I've reached FG?

I still suggest just dropping the hydrometer(sanitized) in the fermenter which will be a reading we can trust. You will have to bottle immediately after the contact with air though.

1.020 is about ~25g of sugar in a ~50cl bottle. Drink it, does it taste sweet? At 1.020 I think you might be able to tell by taste. I wouldn't trust it if it doesn't seem sweet, but if it is, then there is a good chance it's stuck.

It should be fine to bottle, but I wouldn't push my luck considering the risks involved with bottle bombs. It's a slim chance for them to explode, but you are ****ed if they do. After priming, I would open a bottle once every few days and keep in the fridge at a temperature it can't ferment once it reaches the desired carbonation. Treat them like you would treat an empty gun. You are likely fine, but don't take the risk and act as if it could go off any second.

 

[bracconiere]

2) hydro sample was very cloudy and full of trub (but I thought that wouldn't matter)

did you try to push the hydrometer down, and see if it floated back up to 1.022?

 

[Velnerj]

did you try to push the hydrometer down, and see if it floated back up to 1.022?

Yep, always comes in at 1.022.

 

[BrewnWKopperKat]

is it possible I've reached FG?

Extract or all-grain recipe? Measured or software estimated OG? What attenuation rate was used for MJ M15 Empire Ale when estimating FG?

 

[madscientist451]

At bottling I took a sample to measure with my hydrometer. 1.022!!! This sample was taken without priming sugar added... Refractomer reading is the same still (8 brix). I'm afraid now of bottle bombs :-(

Should I be worried?

So....If you took a sample BEFORE adding priming sugar and it wasn't what you expected, why go ahead and bottle the beer?
Next time, take a sample, check the gravity, if you don't think its done, bring the fermenter to a warmer place, swirl it gently, and then check the gravity 3 days later. If its the same, its done.

 

[GilSwillBasementBrews]

The refractometer and hydrometer readings are different due to the presence of alcohol skewing the refractometer reading. They are meant to measure the amount of sugars in water. The alcohol thins the water and skews the reading. Final gravity should always be taken with a hydrometer reading for accuracy. There are calculator that can adjust the refractometer reading to more accurate readings with alcohol present. As noted your two reading the same with refractometer do show it was finished but the gravity reading is wrong as not adjusted for the presence of alcohol. So it can be used to show fermentation completion but not an accurate final gravity without adjustment.

 

[Velnerj]

Extract or all-grain recipe? Measured or software estimated OG? What attenuation rate was used for MJ M15 Empire Ale when estimating FG?

All grain. The estimated OG is about 1.015 just based on a 75% attenuation from the Yeast manufacturer's (MGJ) estimated numbers. So when I read my refractometer at 1.013 I figured it was done.

 

[Velnerj]

The refractometer and hydrometer readings are different due to the presence of alcohol skewing the refractometer reading. They are meant to measure the amount of sugars in water. The alcohol thins the water and skews the reading. Final gravity should always be taken with a hydrometer reading for accuracy. There are calculator that can adjust the refractometer reading to more accurate readings with alcohol present. As noted your two reading the same with refractometer do show it was finished but the gravity reading is wrong as not adjusted for the presence of alcohol. So it can be used to show fermentation completion but not an accurate final gravity without adjustment.

I am well aware of this. The reading of 8 brix with after being run through a correction formula turns out to be between 1.013 and 1.0015 final gravity depending whose formula you use. Sean Terrill's (probably one of the best) shows 1.015 which, although slightly high, could certainly be the FG for this beer.

I just don't understand how the hydrometer could show 1.022 and the refractometer correction formula be so far off as I have never encountered this before. Every time I have had the refractometer and hydrometer agree (and yes my refractometer is calibrated).

 

[Velnerj]

So....If you took a sample BEFORE adding priming sugar and it wasn't what you expected, why go ahead and bottle the beer?
Next time, take a sample, check the gravity, if you don't think its done, bring the fermenter to a warmer place, swirl it gently, and then check the gravity 3 days later. If its the same, its done.

Point taken. Truth is I didn't check the sample I pulled with the hydrometer until after I bottled. I was pretty confident that I had reached FG due to the time and the refractometer reading (which btw has been the same for more than 3 days of fermentation). I have never had a situation like this before where the refractometer (corrected) reading was that much different than the hydro sample. I'm still a bit baffled why it is so...

 

[bracconiere]

off the wall thought, i know you said you checked it in water and got 1.000....but when's the last time you scrubbed the hydro down good?

not sure if that would some how make a difference in beer, and not water, but throwing ideas out....

edit: one more thought....20% is a lot of crystal for a recipe, maybe the carmelized sugars were effecting the calculators correction?

 

[Velnerj]

off the wall thought, i know you said you checked it in water and got 1.000....but when's the last time you scrubbed the hydro down good?

not sure if that would some how make a difference in beer, and not water, but throwing ideas out....

edit: one more thought....20% is a lot of crystal for a recipe, maybe the carmelized sugars were effecting the calculators correction?

I haven't ever scrubbed my dydrometer I've only ran under tap water.... But I still don't think that would cause a problem...

20% of Crystal is a lot, I totally agree. I was just trying to emulate the grain bill for the Boont amber.

After sitting in the graduated cylinder for 24 hours at room temperature, I noticed no change. The "beer" really didn't clear up nor did it show signs of continued fermentation.

I decided to crack open one of the bottles and test that sample. Knowing that there would be a boost in gravity due to the priming sugar. The beer was much clearer and free from trub with a few small bubbles (corbonation had started already). It was at room temperature (around 21C) and the sample read 1.022 same as hydro sample without priming sugar (added 105g to 18L)....

The two samples definitely tasted different, the one from the bottle being noticiably sweeter.

It makes me conclude that final gravity has been reached and falls in the neighborhood of 1.018 +/- but time will tell....

 

[ncbrewer]

Using mangrove Jack's M15 Empire Ale Yeast.

I've had three really slow fermentations (29, 40, and 73 days). these were all with Mangrove Jack's yeast - I no longer use it. You might have the same problem.

 

[bracconiere]

haven't ever scrubbed my dydrometer I've only ran under tap water...

sugar is sticky, and stratification is real.......

edit: i'd recommend if this happens again...soap and water and a wash cloth or sponge to clean the hydro....(as an experiment)