Judging alcohol level

[redhotitfc]

I have started a brew I want to get as strong as possible so I added 1 kg of sugar to a dj at the start and after 4 days will add another 1 kg split over 5 days every 2 days. I want to do this so the yeast can get used to the alc levels increasing.

My main concern is how do I judge the alcohol level. I have taken the sg at the start but as I add more sugar how do I work that out?

 

[31bb3]

I'm not sure tbh a couple of the members can advise you I think Moley is quite up on it also evanvine may do

 

[oldbloke]

If it were to all ferment out, the rule of thumb 20g/l=1% would say that 2kg/5l=20%
Or slightly more, given your demi will probably be a bit under 5l
But then, it's unlikely to all ferment out unless you used one of those nasty turboyeasts
So...
2000g/4.5l is 444g/l is about 1166
Take your final gravity, calculate the drop from 1166, divide by 7.36 = %ABV

 

[redhotitfc]

thanks oldbloke that's perfect!

 

[Moley]

If you know original gravity and original volume then gravity and volume of additions there's something called a Pearson square to work out the totals, but I find it easier to work backwards from known sugars.

100g sugar in the litre gives 36 gravity points, so 100g = 1.036, 200g = 1.072, 300g = 1.108

There's a limit to what the yeast can tolerate though. A good general purpose wine yeast should be able to cope with around 18% alcohol before it kills them, they are swimming in their own waste, we happen to like that waste but it poisons them in the end.

In practical terms, the highest you can ferment from (unless you want to end up with a sweet wine) is around 1.130 which represents 360g sugar in the litre, so 2kg in a demijohn is too much, those yeasties will only be able to use about 1650g.

 

[bobsbeer]

I use this page quite often when calculating sugars. HERE

 

[redhotitfc]

Thanks all. I put in 1.60kg at the start now and got an OG of 1.124. So looking for about 17.6% I think. Just straight up yeast, water, nutrient and sugar. Going to take some good advice from here and add Sodastream apple syrup and some malic acid to make it sour apple. Probably some green food colouring to make it a very dark green.