Slick, my vet, too, was concerned about K'Cee getting enough potassium; he said (for us) this is where the hairball remedies come into play. I give this to her every other day. It's cheap, about $12.00 a bottle. That might be a "maintenance" option for Max after the potassium shots.

Forgive me if this has already been posted but I've found a wealth of information here: CRF Cats.

And for what it's worth, I've had tremendous luck (thank you, God!) with Azodyl. That might be something you ask about if you haven't already. From what I understand, Azodyl is "internal dialysis" so to speak; it increases good gut bacteria which in turn helps break down certain toxins, resulting in a lower BUN level.

Still thinking and praying for you guys.