I've got a batch of Carignane wine aging in the carboy right now and
have a question about how much sulphite to add at each racking. Here's
what I've done so far:

50 ppm sulphite at crush, 50 ppm sulphite at the first racking (after
ML fermentation was finished in November). My plan is to do a 2nd
racking, adding oak chips, then leave it till the Fall - do a 3rd
racking then bottle a week or so later.

Given the sulphite I've already added, how much should I add at the 2nd
and 3rd rackings? pH is 3.55-3.60.

Thanks!

The better and safer way would be to measure the free SO2 before
racking and do the addition based on that. If you want to ballpark it,
then I'd suggest 20-40ppm at the 2nd racking, probably closer to the
end of the range to be safe. I'd definitely do the free SO2 check on
the next racking if you're planning to bottle right after, aiming for
30ppm or so at bottling.

Pp

On Jan 9, 5:11 pm, "Trav77" > wrote:
> I've got a batch of Carignane wine aging in the carboy right now and
> have a question about how much sulphite to add at each racking. Here's
> what I've done so far:
>
> 50 ppm sulphite at crush, 50 ppm sulphite at the first racking (after
> ML fermentation was finished in November). My plan is to do a 2nd
> racking, adding oak chips, then leave it till the Fall - do a 3rd
> racking then bottle a week or so later.
>
> Given the sulphite I've already added, how much should I add at the 2nd
> and 3rd rackings? pH is 3.55-3.60.
>
> Thanks!

pp wrote:
> The better and safer way would be to measure the free SO2 before
> racking and do the addition based on that. If you want to ballpark it,
> then I'd suggest 20-40ppm at the 2nd racking, probably closer to the
> end of the range to be safe. I'd definitely do the free SO2 check on
> the next racking if you're planning to bottle right after, aiming for
> 30ppm or so at bottling.

How does one calculate how to add 20-40ppm of SO2?

Pino wrote:
> How does one calculate how to add 20-40ppm of SO2?

Potassium metabisulphite salt contains 57% free SO2 (by
weight). For x liters, to get y ppm (parts per million) = y mg/l (y
l)/ (0.57) = grams of potassium metabisulphite salt.

For 23 liters, to get 40 ppm (parts per million) =
(40 mg/l x 23 l)/(0.57) = 0.99 grams of potassium
metabisulphite salt.
HTH,
Guy

On Jan 11, 2:39 am, "Pino" > wrote:
> How does one calculate how to add 20-40ppm of SO2?

Guy's answer gives you the exact amount. If you don't have a precision
scale, a reasonable compromise is: 1/4 teaspoon of potassium meta gives
about 50ppm of free SO2 for 5 US gals, so dilute this in a known amount
of water - say 20-25 ml - and then calculate how much of the solution
you need for your volume.

Ex., to get 20ppm for 6 US gals: the whole amount of 20ml would give
(50ppm x 5 gals) / 6 glas ~ 42 ppm for the 6 gals, so to get 20ppm, use
(20ml x 20) / 42 ~ 10ml of the solution.

This is not as precise but good enough as long as the 1/4 tsp
measurement is reasonably correct - Iverson recommends getting the
spoon form a pharmacy instead of using the usual kitchen tool.

Pp

pp wrote:
> On Jan 11, 2:39 am, "Pino" > wrote:
> > How does one calculate how to add 20-40ppm of SO2?
>
> Guy's answer gives you the exact amount.
> Pp

Wrong pp! I gave the right solution but the wrong answer.
For 23 liters, to get 40 ppm (parts per million) =
(40 mg/l x 23 l)/(0.57) = 1614 mg or 1,61 grams of potassium
metabisulphite salt.

Easier solution is 40g x 23 l /570 = 1,61 g

Guy

Guy,
You sure you want to divide? I think you need to multiply: 40mg/l*23
L*.57 or around 1/2 g.
Joe

guy wrote:
> pp wrote:
> > On Jan 11, 2:39 am, "Pino" > wrote:
> > > How does one calculate how to add 20-40ppm of SO2?
> >
> > Guy's answer gives you the exact amount.
> > Pp
>
> Wrong pp! I gave the right solution but the wrong answer.
> For 23 liters, to get 40 ppm (parts per million) =
> (40 mg/l x 23 l)/(0.57) = 1614 mg or 1,61 grams of potassium
> metabisulphite salt.
>
> Easier solution is 40g x 23 l /570 = 1,61 g
>
> Guy