Managing SG readings if gradually adding sugar?

Winemaking Talk - Winemaking Forum

Help Support Winemaking Talk - Winemaking Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Jul 18, 2009
Reaction score
Hi, I've followed a few recipes that called for sugar to be added gradually. E.g. 50% at start of primary fermentation, and the remainder after 3 days.

To date, I've never had confidence in the use of my SG readings to calculate abv because they'll be going down then up then down again and I am not sure what is the official "start". Here is an example of a batch of grapefruit wine(starting SG seems too high in retrospect, my notes are a little old).

Initial SG (on pulp and 50% of sugar) 1.120
3 days later 1.060
Added remaining sugar 1.100
Finished fermentation at 0.996

Yes, it turned out very dry. Is it as simple as taking the 0.040 increase caused by the second 50% of the sugar and adding that to starting SG, e.g. 1.160? I said it was dry but putting these numbers into FermCalc I get 20% abv. It wasn't that dry!

1st WHY make a wine starting @ 1.120? that will give you 16% wine
2nd WHY are you adding MORE sugar? You will get Rocket Fuel...
3rd What are you making?
4th the amt of alcohol does not make a dry wine. A dry wine is when all the fermentable sugars are converted to alcohol.
Easy guys, this was like my second batch ever - I'm still learning. The quantitites I used were as per the recipe, in fact I reduced the amount of sugar believe it or not. The recipe was for "semi-sweet grapefruit wine" however I used EC1118 yeast at the recommendation of my local home brew shop. Thinking about it now and having read a few other posts here, I suspect that the recipe probably assumed a different yeast that would stop fermenting earlier and leave more sugar behind.

Anyway, before we get into a debate about this particular batch can you give my original question another thought:

1. Do you often add the sugar at intervals, separated by periods of fermentation like my recipe advised (and my "Beginner's Winemaking" book)?
2. If so, can final alcohol levels still be calculated using SG readings? i.e. SG may start high, then go lower, then increase again when you add more sugar, then start to drop again.
3. Or should I just adopt a policy of adding all the sugar at the start, taking a single starting SG and that's it?

Hmm, so I am misusing the term "dry" - sorry.

I wasn't trying to start a debate , I was being my normal smart a$$.
Only time you add sugar as you go is to up alcohol. I have also, played with rocket fuel so I have no room to judge, as most here have.As far as a set interval goes , it will depend on yeast, speed of fermentaion, temp, and what you are fermenting. I add when sg gets low enough not to to take it to high as to kill or stunt the yeast when I add.
Personally I would start with a plan not to add during fermentation , ferment dry then backsweeten
I see no advantage to adding sugar during fermentation. that being said I add sugar to my fruit wines to get the desired starting gravity readings. If doing wine from grapes you should already be @ the gravity needed for that profile.
Reading over my notes again I realize why my SG was so high. In attempting to follow the recipe I had taken some of them at times when I hadn't added the full volume of water.

Because the recipe also calls to add the yeast while the pulp is still in the fermenter, and not at the final volume of liquid, I'm not sure I would be able to get a useful SG measurement using this method.

What I did instead was used FermCalc to approximate initial SG based on amount of sugar added and amount of fruit, which lead me to calculate the final alcohol % at about 14% which sound a bit better to me.

I guess I'm not going to be able to get an accurate starting SG unless I juice the fruit and make it up to full volume before starting fermentation?

I've been steeping the pulp in muslin bags for all my previous batches, as much as I'd like to be able to juice or press everything, I think I might just stick with steeping.

Latest posts