The water is for the brix level.

The pH adjustment is, in my understanding, for protection of the wine by
SO2. At higher pH it takes more free SO2 to get the same molecular SO2
level.
The tartaric acid addition is for pH reduction. The precipitation of
potassium bitartrate will use up tartaric acid. Thus you can achieve a
lowered pH without excessively high TA.

You want to keep the pH no higher than 3.9. If you let it get above
4.0, you risk not being able to lower it using tartaric acid additions.
My understanding is the chemical reaction of potassium with tartaric
acid to reduce pH will not occur above pH 4.1.

One may adjust the pH downward with tartaric additions to pH 3.7 at the
next to last racking before bottling, allowing time for the
precipitation of the bitartrates. This will allow for reasonably
efficient protection of the wine by SO2 after the wine is bottled.

Gene

wrote:
> Lum,
>
> What's the advantage of ameliorating the must over adding tartaric
> acid? Why would you water down the grapes? Is it the brix level? Would
> you add water if the brix was 26 to start to adjust the ph? Do you, as
> a rule ,leave the ph and only adjust the brix if too high?
>
> TIA
>
> Bob
>
> On Nov 14, 8:07 pm, "Lum Eisenman" > wrote:
>> "Darin" > wrote in message
>>
>> ...
>>
>>
>>
>>
>>
>>> Today, I will take delivery of 1/2 ton of premium Napa Valley Cabernet
>>> Sauvignon, courtesy of the Caldwell vineyard and Peter Brehm. This is
>>> by far the most expensive barrel we've ever made, and fittingly it
>>> promises to be the most challenging.
>>> Every variable seems to be extreme, including 28 Brix, pH 3.80, and TA
>>> at 0.67. My goal is to make a "big red California fruit bomb",
>>> without excessive intervention.
>>> Hopefully, the masters of this news group can give me some guidance
>>> and I can thereby avoid screwing up what has potential for an
>>> incredible vintage.
>>> The first thing I'm going to do is confirm the chemistry and then
>>> ameliorate with acidulated water (7g/L) to reduce brix to 24.5 (I'll
>>> remove as much free run as water added).
>>> Then I'll have a look at TA and pH and see where I stand. I'm
>>> considering raising the TA to as high as 0.75 to get what meagre
>>> decrease in pH might be possible. Then, with a pH I expect to be
>>> around 3.7 - 3.8, I'll have to start the ferment, follow with ML,
>>> press, and then send the sulphited wine to the cool cellar to age,
>>> precipitate KHT, and enjoy life in its new oak barrel.
>>> Does this sound reasonable? In the past, I've always used the rule of
>>> thumb that pH should be less than 3.5 before fermenting. I don't want
>>> an overly acidic wine, though - isn't that the California approach
>>> these days (4x4)?
>>> Thanks much in advance,
>>> Darin
>> Darin,
>> That is the only kind of red wine I make.
>>
>> I would add about four gallons of plain water to the 1000# of grapes.
>> Should produce a Brix of about 26+ and a TA of 0.63 or so.
>> I would ferment with Prise de Mousse or Premier Cuvee yeast.
>> Punch down the cap at least four times a day.
>> Press after 7 or 8 days on the skins.
>> Start MLF.
>> Add 50 mg/l of SO2 when MLF is finished.
>> Age in a neutral barrel for ~12 months.
>> Raise SO2 to 0.5 mg/l of MOLECULAR sulfur dioxide and bottle.
>>
>> Don't mess with these high quality grapes and don't be afraid of high pH
>> wines (see www.vinovation.com/ArticleWinepH.htm).
>>
>> Good luck,
>> Lum- Hide quoted text -
>>
>> - Show quoted text -
>