What to check with Cabernet juice

[ABC]

I am making Cabernet for the fourth time from juice I buy from Italy and Chile and I have had some good results so far. I have always used a hydrometer so that I know when fermentation is complete but I have never checked pH or brix. Is this something I should be doing with juice or would this only be used if I was buying grapes? Now that I have started fermenting a new batch a few days ago, can I still make changes to pH and brix or would I have to do that before adding yeast?

Thanks in advance.

 

[pillswoj]

Starting SG or Brix is always nice to know so you have an idea of alcohol content of finished wine, pH or TA may have been adjusted in the juice before you received it, but can be adjusted after fermentation if needed.

Most juice buckets will state the Brix or SG and the Acid / pH on the pail when you buy them.