Metabi is used quite regularly for sanitation throughout the wine industry
(I work for a winery myself). Yes at higher pH there is less molecular, but
this is less molecular per gram of metabi added to the liquid. When you're
using water you can add as much metabi as you wish to reach the
sterilization amount as the minimum molecular or more (ie 1000ppm 10000ppm
....it doesn't matter) an amount which would never be added to a cherished
wine! In wine however, most winemakers don't feel comfortable adding such
grand amounts. But when its just dissolved in water you can make whatever
concentration you wish to achieve.

"Neil R." > wrote in message
...
> it is the molecular sulphur dioxide content of free sulphide dioxide that
> protects wine from oxidation and microbial attack. the content of
molecular
> sulphur dioxide in the free sulphur dioxide depends on the pH of the wine
> with lower pH's having the higher content. eg. pH 3.0 = 6% , pH 4.0 =
0.6%
> therefore it would seem to me if u r using metabisulphite as a sanitising
> agent for equipment and bottles it is useless unless the water used is
> acidified to at least below a pH of 4.0.
> any comment?
> neil
>
>