I have been asked how a wine can have a high pH and high acidity when one would normally associate low pH with high acidity.  pH measures the concentration of hydrogen (or hydronium) ions in a liquid.  The greater the concentration, the lower the pH.  The level of potassium in the grapes can cause a high pH -- high acidity condition.  The source of the potassium could be in the soils or from not fully ripened grapes.  The potassium can bind with tartaric acid and prevent the hydrogen ion from going into the solution to be measured by the pH meter.  This is referred to as a "buffer" whereby there is a resistance for pH to change.  On the other hand, when one measures the acidity, it will result in accounting for the hydrogen ions that are bound up.  Winemakers prefer wines that are more balanced in their pH and acidity.  This is why good wine starts from sound vineyard practices in maturing the fruit.