I discovered the problem with the acidity level in birch reacting with copper yesterday. I had to throw the whole batch out. Dammit.
My understanding about the duration for tapping is much the same as Maple. When the buds come out, the season is over. I was hoping someone else would chime in to tell the both of us. This is my first time ever with birch and have only tapped maple for 3 years now.