Can I add extra sugar to restart my fermentation?

[PieterThyssen]

This is the first time I'm trying to make Elderflower champagne. And I could really use some help of more experienced home brewers.

I wanted to make 25 L of champagne with an alcoholic content of 8%. Using the simple (perhaps too simplistic?) formula:

Sucrose needed (in g) = Amount of wine (in L) x Alcoholic content (in %) x 16,

I figured I needed 3200 g of sugar. To this I added Elderflowers, lemon peels, lemon juice, yeast nutrient, and champagne yeast.

The initial SG was 1047, which corresponds to a sugar content of 125 g/L according to my hydrometer. This seemed correct, since 3200 g / 25 L = 128 g/L.

The primary fermentation went really well, maybe too well. The bubbling in my airlock started on day 1, reached a maximum on day 2, decreased on day 3, and basically stopped on day 4 (today).

So I decided to rack my brew into a secondary glass vessel for the secondary fermentation, but when measuring the SG today I only had 910 (??!!). Can it even be that low? I tasted some of the wine, and it tastes very dry.

So it seems ALL of the sugar has fermented in just 4 days, and a secondary fermentation won't happen anymore.

My question is now, can I restart the fermentation by adding extra sugar in order to increase the alcoholic content?

The idea is to dissolve another 1600 g of sugar. This should be enough to raise the alcohol content to 12% (according to the above formula).

I would dissolve the sugar in 1 L of water, boil it, and let it cool. I could then remove 1 L of my brew before adding the 1 L sugar solution, to retain the same total volume of 25 L. And then hoping that fermentation will start again in my secondary vessel.

Could this possibly work? Thanks so much for your help, advice, remarks or ideas.

Cheers, Pieter

 

[PieterThyssen]

Sorry, the SG is not 910, but 992 right now.

 

[Yooper]

Sorry, the SG is not 910, but 992 right now.

That's perfectly normal- most wines will finish at .990-.994 or so, usually on the lower end of that.

You can add more sugar to increase the ABV if you'd like. No reason to take out any of the volume- just add the sugar. If you want to dissolve it, you could dissolve it in a little hot water, let it cool and add it.

 

[PieterThyssen]

Thanks Yooper for your prompt reply!

I made a solution of 1 kg of sugar in 1 L of water, boiled it, and let it cool to 24 °C.

I then added 300 mL of the syrup to my brew, and I'm happy to say it seems to work! Bubbles are produced in my airlock at a slow rate of one bubble every 30 seconds.

Tomorrow afternoon, I plan to add the remaining 700 mL of syrup.

Thanks again and have a wonderful day! Pieter