How do you know when to change crystal litter?

I was traveling with a friend recently and she brought crystal litter to use in the hotel room. The kitties really like it, and I like that there's no dust. I'd like to try it for my cats at home but have questions about exactly how it works. I know the urine is absorbed into the crystals and you only have to scoop the poop. How do you tell when the litter is used up? I don't really want to wait until it starts stinking, but I don't want to throw it out too early either.

I think you change it when it has turned yellow and is no longer absorbing urine. That was the stuff Jamie scratched completely out of the box and down the staircase when I tried it, so it never got the chance to change color. :lol3:

In my experience, the crystals turn yellow when they absorb urine. Because of this, I would scoop out those crystals and add clean to replace (likely not the way it was intended, but it bother me too see the used crystals sitting in the box.)

If you left the used crystals and only scooped the poop, I would think you would need to dump the box every 2 weeks or so. But, that would also depend on the number of boxes to the number of cats you have.