First off: Sorry for the link, apparently I can't upload images at the moment.
This is my first ride with a wireless hydrometer, so maybe this is just me not being used to having access to gravity readings all the time, having become a bit obsessed with the numbers. Looking at Brewfather on the other hand though, my gravity really hasn't changed for like 36 hours now, before reaching its estimated final value. Now I'm afraid that my fermentation has stalled, and as the gravity was never really high to begin with, I fear being stuck with something not only low in low in alcohol but also tasting thin & weak. This is supposed to be a "Klosterbier" (not a real beer style, but closest described as some sort of brown ale), with which I'd have preferred to err on the stronger side rather than on the weaker.
The main reason for the low initial gravity I believe is too little boil off: While pre-boil gravity was OK (Brewfather predicted 1.039, refractometer gave me 1.037, might even be considered to be within measuring tolerance), the post boil reading should have been 1.051 but was only 1.041.
After boiling, I took around half a liter of wort, chilled it down in a mason jar and added dry yeast, agitating it every now and then. The next day, I pitched now very agile yeast into the main bucket and fermentation started out perfectly. The ups and downs in the graph may just be results of krausen and/or condensate dripping back onto the RAPT pill or creating ripples in the wort surface.
Now, I'm really asking myself what went wrong. I don't think I caught myself any infection, the bucket was properly sanitized as well as the collection vessel & I was very careful handling all of it. The yeast also very happily ripped through the major parts of the sugars, so I don't think it's a yeast issue either. My grain bill looks as follows:
2.25 kg (50%) — BESTMALZ BEST Munich — Grain — 15 EBC
2.21 kg (49.1%) — The Swaen Swaen Vienna — Grain — 10 EBC
40 g (0.9%) — Weyermann Carafa Special II — Grain — 1100 EBC
The performed mashing steps:
Mash In — 38 °C
Protein Rest — 50 °C — 40 min
Beta Rest — 63 °C — 30 min
Alpha Rest — 72 °C — 30 min
Mash Out — 78 °C
I'm not sure what to do, or if I should do anything at all. I can live with the beer having 3.5% ABV like it has now probably. My storage is dark and reasonably hygienic, so I don't think I have to elongate the beer's shelf life that way. The alcohol might then even overpower the taste of the grains if I added table sugar or anything for another percent of alcohol.
What I'm slightly concerned with though is overwhelming hop aroma because there apparently is not that much dissolved sugar to counteract the bitterness.
Any suggestions?
For everyone involved and/or curious: I took a regular hydrometer reading last evening, which gave me ~1.011/1.010. So while not too far off, that is still significantly lower than what the Pill sees. Also, when taking some more time to observe, I realized that there is indeed still airlock activity going on. Now that I was sure there was still CO2 being produced, I then peeked under the lid and saw that the Pill had collected quite some dried trub on its waterline. After seriously sanitizing everything, I took it out, cleaned it and pitched it back, though that didn't result in more realistic measurements. So I guess it's down to a calibration issue.
What a stupid situation: The only at least halfway reliable measuring instrument after fermentation start remains the saccharometer, which requires a sample of 100 - 200 ml for each measurement, so you can't do this every day for an elongated period of time without losing significant amounts of product for a batch if this size. Only alternative would be a transparent fermenter like the FermZilla and leave the saccharometer afloat the whole time. Not sure if I like that idea.
At least I got a taste sample this way and I'm happy to report that there is nothing weird going on. It's not the biggest beer in the world, but summer is coming anyway, so that's only a half bad thing. I'll report back with pictures in a few weeks after conditioning. Cheers!
uh thanks for the update! I'm happy your beer is coming along nicely. personally I wouldn't bother with hydrometer readings during fermentation. it sure is nice to see the numbers change but i find airlock activity to be just as good. i take a final reading after bubbling has stopped (only because I'm curious, never used the value for anything), and call it a day. anyways cheers!
I have my fermenter exposed to rather significant temperature deltas, so airlock activity maybe is not the best indicator in my case as the air inside expands and contracts.
It would suffice of course just to measure daily with the refractometer to see if there still is activity. Not having to though is a tempting idea to me. 😄
i can see your issue here. but wouldn't you want to aim for a somewhat constant temperature during fermentation? my understanding is that yeast will produce different aroma profiles with different temperatures. so depending on the style you are aiming for on would choose a different temperature.
https://www.homebrewersassociation.org/how-to-brew/understanding-fermentation-temperature-control/
Yeah, constant temperature is good, but mine only went up and down like 4 °C tops. That the coldest of night vs. the hottest of day. It's not nothing, I'm aware, but overall, I guess it's stable enough. In my Vienna Lager, the higher temperatures made the W-34/70 eat up that diacetyl really well apparently.
I'll aim for more stable temperatures in the future so, as already wrote somewhere here with a little enclosure I want to build for my fermenter to even out mins and maxes.
in my mind 4°c is sufficiently stable and should be stable enough to not have me worry about volume contraction influencing airlock activity. wikipedia says volume contraction should be minimal at these temps https://en.wikipedia.org/wiki/Thermal_expansion
I'd say two days at your average temperature without airlock activity is sufficient to call fermentation done. cheers
You may try refractometer with correction and then using hydrometer before bottling/when you need exact measurements. Other options are too expensive for homebrewers, like in our brewery we use device from AntonPaar that uses about 10ml per measurement. It costs about 5-10 times more than the pill.