i've got a batch of okanagan merlot that began the ferment @ pH 3.35
with TTA 6.0 (yes, i corrected a bit). with MLF complete, and S02
added, the wine has been in my cellar (9-10 degree C) for over a
month. at present, the pH has got rather high (3.79), the TTA is
indicating 5.8, and my free S02 is 35ppm. i'm not a terrible chemist,
and i have some faith in my numbers, derived by vacuum aspiration. so,
i pose two questions with respect to this endeavour:

1. to get the optimal (minimal) amount of mol. S02, it appears i need
around 50ppm free. i have both the australian chemistry and winemaking
guides, and they speak of only 15-20ppm required for red wine storage,
although a caveat mentions that you'll need to go a bit higher for
pH's above 3.5. I realise that my pH of essentially 3.8 would require
something past the 'slightly' higher value of 20ppm. Is my current
35ppm safe for my 400+ litres of Merlot?

2. i tested a 2002 Quail's Gate Merlot, which had a pH of 3.65. I was
shocked to find the free S02 measured less than (probably much less)
than 16ppm. a same vintage wolf blass shiraz, pH 3.5, weighed in at
14.5ppm free S02. Why are these numbers so low? Is it just that the
wine will be consumed quickly and not cellared for a long time, or is
there something else at hand?

Many thanks for any opinions or answers.
Darin