Concur with Atribune
SG will determine when the primary fermentation is complete. Typically, this occurs when a SG is at 1.000 or less. This is considered ferment to dry. Some kits will have you rack the wine when the SG is at 1.010. This is referred to as racking to the secondary....reality... its a continuation of primary fermentation until the must reaches 1.000 or below.
Below is some info on PA or what I think you mean is TA or Total Acidity:
In the U.S., the total acidity (TA) of a wine is measured assuming all the acid is tartaric. This allows one to determine a value for total acidity that is consistent. A high TA is 1.0%. Most people would find this level of acidity too tart and too sour for consumption. A low TA, say 0.4%, results in flat tasting wine that is more susceptible to infection and spoilage by microorganisms. Most red table wines are about 0.6% total acid. White wines are usually a little higher.
pH is a measure of a solutions acidity and is analogous to the Richter scale used to measure the intensity of earthquakes, since both scales are logarithmic. For example, wine with a pH of 3 is 10 times more acidic than a wine with a pH of 4. The thing to remember about pH is that the higher the pH, the lower the acidity, and the lower the pH, the higher the acidity. So a wine with a pH of 4.0 is LESS acidic that one with a pH of 3.6. Although total acid and pH are related, they represent different ways of measuring acidity of wine.
hope this helps