Like someone has already said, test your water. I do not and do not plan on keeping birchirs, nor know anything much about them. However, I do know that you should test your water. If you don't have a testkit, take it down to your lfs, who should test it for you.
I agree, puffer = bad idea, set it up in its own tank, it will be much happier.
Just one question, how odes the puffer act? He will be one of the first to tell you your water is wrong, and even if you don't know, you could describe it, and I will try and tell you.