I am not very diligent about scooping, so I change the box completely every week. I use dish soap and hot water and scrub it with a brush. B/c I am not good about scooping, the clumping litter gets clumped on the bottom of the box. Sometime I spray non stick cooking spray or lately I have been spraying Lysol on the bottom of the box as a precaution to kill germs. Just something I started doing, not sure why.
I just filled a new litter box that is a sifting box. So we shall see how that works. I really wanted the box that rolls and all the clumps go to a little resevoir that you just throw away, but PSP doesn't have any.