I couldn't agree more about how rats seem to love the triangle litter boxes. They are also a lot more difficult for the rats to dump over.

Some cat litters work great, but I wouldn't suggest using a silica clay based litter with anything. Clay is very difficult for the body to eliminate, and breathing clay dust has long been associated with diseases in people such as Farmer's Lung. So imagine what it would do to something with even more delicate lungs than us.

Not to mention, rats like to taste everything and clay litters can be fatal if ingested.