I have the urge to make a melomel with orange blossom honey and freshly squeezed grapefruit juice. Knowing that this will be quite acidic, I was planning to raise the pH to a about 3.3 or so with CaCO3 and/ K2CO3, but my question is: what is the upper limit of Ca and K ions that yeast can tolerate- because I figure it might take pretty much K2CO3 and CaCO3 to reach a PH that the yeast will ferment at. Any thoughts from you experts?