Slow fermentation...

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Sep 9, 2022
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Hello community,
I've been brewing for quite a while now and finally have had to ask for help on a strange one which might be an interesting one for you!
I've recently upgraded my brewing to a wine cooler with my fermenter having a thermowell and a heat belt supported with an inkbird!
However, I've recently brewed a Mangrove Jack's Bavarian Wheat kit, and its been fermenting for over a month.

It started just below target OG of 1047 by a couple of points 1044 and I used the 1.2kg of thier liquid extract (light) and its only at 1026 after month. I'm still getting pressure build up on the lid and I have a blow off tube not a bubbler.

I was wanting more clove taste so brewed at 19° then after 2 weeks I was thinking it was stalled and roused so increased to 23.

Now it's been tasting okay however the time its been in it doesn't seem to be fermenting any further. Which is strange and thinking that its just fermenting at an incredibly slow rate. It was well oxygenated, good pitch temperature, good sanitation. And I roused it at week 3 which seemed to kick it into life a bit. The fermenter doesn't have the best lid but enough to at least show pressure against it.
I'm using a refractometer, and tested against hydrometer with same results.

So thought I'd see if there were any ideas. Like needing nutrient, more yeast...but I think this brew maybe for the drain. With it being fermenting so long I'm worried about other things that might be increasing in concentration in it.
i know you said you compared the refrac to the hydro...but i'd be curious what the BRIX on the refrac was anyway? if it's ~6.5, then you have a FG of ~1.014
Ah! Is the conversation on the scale on a refractometer not in line with brix on the refractometer? It has brix and SG scales side by side on the view aperture.
I was told by MJ that the ingredients should get me to 1016 after full fermentation. I was thinking about testing the temperature of the liquid with a known good thermometer to calibrate the inkbird probe if it needed it, because it was behaving a bit like the temperature was too low when I increased it. But it is a youngs fermenter so CO2 could have just been escaping from the lid. But, SG is what I've been going by. I also never hydrated the yeast this time. Usually do. But. Shouldn't really give a problem?
well...if your refrac is reading 1.026, the BRIX side would be 6.5 right? which would be corrected to 1.014 because of the presence of alcohol.....

i'm not sure what kind of hydro you're comparing it to? how does it read in plain water?
Interesting comments here as I think I'm today years old now haha.
I got the refractometer as a present and a few months ago as I was wanting a better way of testing gallon all grain brews. So I thought that the SG reading was just that same as a floating hydrometer. But thinking I might just go back to my hydrometer and test jar after reading the help here. I'll get some calcs done tomorrow and re test.
I'm today years old now haha.

but you said you compared it to a hydrometer, and they read the same?

and honestly learning that refrac read different when ethanol is present is the only reason i got one! being i ferment a lot of things kinda blindly, but need to know how many calories they have...i can use both, and get a good guess at how much ABV a water/ethanol based liquid has....
The calculations are pretty simple. Bracc is correct in his numbers.

You reported OG 1.044 and FG 1.026. The OG is good, apparent=actual. The FG is skewed high by the presence of alcohol. The light is refracted differently. Apparent does not equal actual.

The Brix readings which correspond to apparent SGs of 1.044 and 1.026 are 11 and 6.5. I used Part I to find those.

Thrown into Part II, it spits out a true SG of 1.015

All that for the price of three drops out of your one gallon batch.
I assume your refrac vs hydro check was with a liquid without alcohol. Like water.

You can still use a refrac for post fermentation, but you will need to use a calculator. there are lots on-line. Just remember this is not as accurate as a hydro sample, but generally pretty close (usually within ,001). The calculators are based on empirical results (actual test results comparing refracs to hydro readings), and can vary depending on the types of sugars. the OG and FG, and other characteristics of the tested samples. No 2 calculators will be EXACTLY the same unless they are based on the same original data.
I am so happy I posted here for all the comments and a huge thank you for the time taken by you for helping me out!
I'm not to unhappy about taking hydrometer tests out of 5 gallon batches but when you do a few tests from a gallon brew your left with even less beer etc etc. Not enough space to do big batches and so on. But I was fairly nubile in the practice of using refractometers but now you've helped me leaps and bounds!

Still a bit confused as to why the main batch I've had still creating pressure at the lid every few days. Hopefully it's just co2 in the batch?
With the blow off tube it takes quite a bit of effort to blow it out. Might play around with a small bubbler as there isn't much room above the fermenter. The blow off tube is below the fermenter so thinking raising it up will be better.
Will go to bottle now as I'm pretty happy with what's I've got back with the calcs here. I'll double check with the hydrometer just before though 😂

One last question, what causes a faint line when looking at a sample through the refractometer? Is it the presence of alcohol or co2?
When testing with water or OG it's a solid line.
Did a hydrometer reading and its just above 1012. Face palm moment.
I think when I took that reading before when they were the same, refrac and hydro, they were actually the same because it was about a week after the brew started.

And it's still tasting good.

Thanks again