Acidity is one of the tests you should doing on your wines. High acid wines aren't pleasant to drink, and wines with not enough will not have good flavor and taste like dishwater. Plus, knowing the acid level will tell you how much free SO2 you should have for preservation.
Actually, those papers for acid tests are pretty expensive. The cheapest way to test acid is with a PH meter. You can find meters for $80. And the best time to check PH is pre-ferment. Getting that acid where you want it will make a big difference in your wines. As an example, we were making peach wine a few days ago. The initial PH was 3.6 and it had no flavor. When we got the PH to 3.35 by adding acid blend, the flavor just exploded. PH directly affects flavor.
If your wines are too acid, add calcium carbonate to reach your target PH. As a very comprehensive guide to PH levels on different wines, some books will state that white wines should have a PH of 3.2 and reds 3.4 Now this is just a guide to get you started---much depends on your own tastes and the type of fruit you're dealing with. We use our PH meter and our tastings while we're adjusting the acid to tell us where we should be. Acidity won't change significantly in the aging of wine---you've got to get it in an acceptable range--and the best time to do this is before you pitch your culture at the primary. This is when you are designing the wine--where the bulk of winemaking is really done.
All our wines are made with no water--so it's really inportant to adjust PH since water will lower acidity to a certain degree but deliver a very pale tasting wine. We make wines with big bold flavors--so we have to keep good PH control in order to have nicely blanced wines. Hope this helps you.
