I pick my fruit (plums in this case) when they're very ripe by taste (I don't have a refractometer) but when I make up the must I get pH's in the low 3 range (3.1-3.3). When I taste the must even at 3.3 it tastes fine -- not too acidic. I add calcium carbonate but ending up using so much (1/2 a cup sometimes) to get it up to the 3.6 range that it makes me really nervous. It just doesn't seem right. And I've heard that using too much of a base can be harmful to the wine/taste. Help.