1. If your must is still in primary fermentation, I'd not add any KMS myself
(crude short-hand for potassium metabisulfite). Wait until you press off
into secondary, then add sufficient to get your ppm to about 30 ppm. If you
add it now, you may only stall the fermentation. But get it in right away at
the next stage to forestall any bacterial prblems - especially with that low
acid. I like to make up a 10% solution of KMS (with distilled water), and
add 2/3 ml. per gallon to move the ppm apx. 10 ppm. Let is stabilize a
couple days, then do a free SO2 test. Repeat until you get it to where you
want it.
2. The pH is OK, but that is a really low TA reading. Not unbelievable, but
surprising. I'd call the lab and ask them to confirm their confidence.
Assuming it is accurate, you might want to start nudging your acidity with
tartaric acid. You can do this slowly, and in increments over the next
weeks. Rule of thumb is to add 3.8 grams of tartaric acid per gallon to move
the TA by .1%. But don't try to make a huge adjustment all at once. Try
moving it in fractions of that amount. Nudge it towards your goal, and keep
an eye on both the TA and the pH. Don't be guided by just one number. Others
here will have great (and better) suggestions; for my own part, I would
probably not want to adjust acid more than taking it to .55 TA, or 3.5 pH -
whichever comes first. And I would likely setle for a pH of 3.6, and/or a TA
of .5 - if it meant not messing with the wine too much.

It occurs to me that you might get caught running back and forth to that lab
a lot. Ever consider getting some basic lab gear so you can test your own TA
and free SO2?

PS - what does a test like that cost you at the lab?




>I took the sample to a lab in St Helena called ETS. Nice folks, I
> asked for Total SO2, pH and TA. So this is the levels on my 60 gal of
> fermenting Cab Sauv fruit.
>
> TA = .40
> pH = 3.63
> Total Sulpher Dioxide = 9 mg/L
>
> It looks like I need to add Tartaric Acid and Pot Met. I originally
> added 11g of Pot Met at crush. Don't I want this to be in the 40 ppm
> realm? It should have been 30 ppm based on 60 gal and 11g Pt Met. How
> much Pot Met and acid should I add? Does anyone have an easy way to
> calculate the amounts?
>
> Regards,
>
> Rick
>