I've had Muffy and the babies using Feline Pine since before the babies were born since it's safe with kittens. Now that the babies are leaving this weekend, I'll only have Muffy and Puffy. How old does Puffy need to be before I can safely change back the clumping litter? He's 8 weeks now, so I know it'll be a while. I'm just really looking forward to having some odor control again!