For use in acid-deficient musts of less than 4.5 p.p.t., add "Acid Mixture A" which consists of 50% tartaric acid, 30% malic acid and 20% citric acid. If the must is acid-deficient but measures higher than 4.5 p.p.t., then add "Acid Mixture B" which consists of 50% malic acid, 30% tartaric acid and 20% citric acid.
I often make my own acid blend depending on the kind of wine I will be making.
An acidblend is nothing more as a mixture of different acids.
I myself like adding cirtric acid to most of my fruit wines when they lack acid as it not only pushes acidity up but also gives the wine some freshness.
However when making flower wines like rosepetal wine or elderflowerwine I make a mixture of equal parts of acid.
Meaning for example 10 gram citric acid, 10 gram malic acid and 10 gram tartaric acid.
This gives the wine some complexity.
Remember that acids not only add acidity but also some (all be it small) flavor.