7 gram/litter , test with a ta test kit , I brought mine up to 6 gram/liter with acid blend, and the last 10 gram/liter with tartaric. Now I will tell you that there is a fellow around corner that makes wine profesionally to sell, he told me that I was low and should bring it up to 8 gram per litter. But I like mine I dont think I will add anymore acid, also most recipe will get you verry close usually a little to the low side. When you bottle it will still taste tart and will fall off over time. I just get close and age in carboy, when ready to bottle try to get acid right on. There are some who do it strictly by taste.
Bob, he was asking about PH not TA. 3.2-3.6 is a good range for almost all wines but just remember that some wines may need more acidity which in turn will usually lower your Ph and apple is one of those or it can taste pretty flat so lower PH and higher TA is more likely the answer here.