"Bruce" > wrote:

> I am at pH of 3.6. Too high by a bit, I guess. This is the second day of
> ferment, going strong. Can I add tartaric acid now? And how much for 35
> gallons of merlot?

Acid adjustments are best made before fermentation begins. You can still
make them now. Take a small sample of the wine, degas it, add tartaric acid
(keeping track of how much you added by weight) until the ph is where you
want it (about 3.4 is the normal target). Then do a bit of algebra to find
the amount for 35 gallons.

If your sample is 8 ounces (0.0625 gallons) and you added 10 grams of
tartaric, you would add: 10 grams / 0.0625 gallons x 35 gallons = 5600
grams.

You should use a large enough sample that you can measure the weight of the
tartaric acid added significantly. If your scale is only accurate to +/- 1
gram, you would need to add about 10 grams before you could extraploate an
accurate figure.