second fermentation

[Thomas]

By second fermentation I hope you mean malolactic fermentation. It is not a good practice to have two yeast fermentations, unless you are producing sparkling wine.

As for malolactic fermentation, you need to control this by first finding a good source for ml. bacteria innoculation and then you must keep close tabs on temperature and completion of the fermentation; the commercial way to check completion is through chromatography (sp); don't know what the amateur way would be.