I would even bother trying to clean the stuff. Just sift out the clumps once in a while, and when it gets kinda yucky toss it all out and go buy a new bag. You can use the hardware store "Play sand" meant to be low-dust for sandboxes and is non-toxic. The stuffs pretty cheap for a 25lb bag it's like $2
And I wouldn't use sand for your leos unless they're adults.