Sulfite addition help

[celladwella]

I just finished my MLF confirmed by the chromatography test. I was going to rack and sulfite now. I have a question if I don’t know what my free SO2 is but I do know my PH how do you know how much to add. My wine is currently in 6 different vessels I have 4 5gal carboys and 2 demijohns worth. My ph numbers were range from a low of 3.79 to 3.99.

 

[Stressbaby]

https://winemakermag.com/resource/1301-sulfite-calculator

Plug in your numbers and type of sulfite. The calculator is not so intuitive in the sense that if you don't know your "desired" you have to click Calculate once to get the desired level, go back and plug that in, and click Calculate again to get the amount to add.

If the wine is "SO2 naive" a lot of it may be bound, so you may have to increase the amount this first time, from 50-100% bump to account for the reduction in free SO2 from binding.

 

[Scooter68]

Well based on all other guidance commonly given for an MLF fermentation NO sulfite should have been added prior to the MLF other than the amounts added pre-fermentation to kill off bacteria or stun wild yeasts.

So you should not have any significant SO2 in a wine that has just finished MLF.

Standard dosage is 1/4 teaspoon per 6 gallons*. You can prepare a concentrated solution of water and K-Meta sufficient for or slightly exceeding the volume to be treated and dose that amount according to the volume being treated. (1 teaspoon in 2 cups of water for 24 gallons 16oz / 24 = .67 oz per gallon in the container.)

* (Some suppliers state 1/4 teaspoon K-Meta per 5 gallons)

 

[Stressbaby]

Assuming no binding, 13% ABV, room temp, your 3.79 wine needs 33mg/L free SO2 which is 0.2g/gal; the 3.99 wine needs 52mg/L free SO2 which is 0.3g/gal. If you think you'll lose a lot of SO2 to binding (tannin, etc) then increase that, up to 2x. Subsequent additions should not need an adjustment.

 

[celladwella]

Thanks Stressbaby and scooter68 Im going to add that very soon