I just did the switch to Silica-you know the crystals, I did it gradually. I like it, I find it controls orders well and absorbs the pee much better. I think he's ok with it, but today he did poop right outside the box. The thing is he did that here and there with clay too. And I saw him go in the silica too another time. He seems to poop right outside the box a couple of times a month, and I don't fully understand it. But he checked out at the vet and is healthy otherwise and at least keeps it on the paper so I am not going to strain myself over it.