Hi Yellowman - and welcome. Do you know the TA of your wine? If the amount of acid (not necessarily the strength of the acid, but the amount) is too high you might need to neutralize some of the acidity but rather than add alkali to the wine you might check to see if adding some more sweetness might "balance" the bitterness. Of course, before you add any additional sugar you would need to stabilize the wine to prevent any yeast from fermenting the sugar and so simply increasing the ABV rather than the sweetness. What is the gravity of your wine at this time?