Fast/slow fermentation

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Jul 4, 2022
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Vancouver BC
Began some peach wine which seemed to go fine. When all action in the glass carboy had stopped for an extended time I decided to bottle. But the wine tasted sweet. SG was below 1.0. The wine store gal said if the SG is below 1.0 the wine is fermented out even if it tastes sweet to you. So I stabilized and bottles. Had a couple of recipes, just averaged the amount of sugar and proceeded. Was just trying for a normal wine. What would account for the sweet taste?

Started at the same time was a batch of blackberry wine. This was in a plastic carboy that I could not see into. At the same time as I bottled the peach wine I tasted the blackberry, very sweet, seemed to be a stuck fermentation. I transferred everything to a glass carboy that I had now acquired, added a bit of grape juice concentrate, put a heating pad under the carboy and waited. Temperature jumped from about 17 to 20. Fermentation took off. Not to the point of foam but lots and lots of bubbles, which now with the glass carboy I could monitor. That was 10 weeks ago and today the batch continues active, the bubbles are not as large and maybe not as many of them. But I consider it still quite active. Does this state seem to be indicative of some type of problem?

17 to 20? Call that about 60 to 70 degrees fahrenheit.
Fermentation usually acts as expected but it's not uncommon to have an oddball in one respect or another. As far as temperature, all fermentations generate heat. I sometimes take a reading out of curiosity and most are about 5 F higher than ambient. My first tomato wine went nuclear and hit 89F, easily 15 degrees above ambient.

And bubbles? Like Bryan said, SG tells a lot. Early on I had a wine in secondary that was still bubbling after 8 weeks and was sure it was slowly fermenting. Losing patience I measured SG and it was .990. My assumption was that it was actively degassing. Now I measure secondary SG after 3-4 weeks.

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