With Igs, it is better to NOT use substrate at all. What I use for most of my enclosures is floor laminate. You can pick it up at Home Depot or some place similar in squares. You just buy how many you need and cut to fit, then tear off the paper backing and press to stick. It makes for a safe surface that cannot be eaten, plus it is REALLY easy to clean.... you just spray (antibac) and wipe up! You can buy it in any color, pattern, whatever you prefer.
This is a pic of my male hovering over his food bowl after eating. I took the pic because he has that look that says "You better not touch my bowl", yet his back legs are just too comical! You can see the laminate I used in his enclosure in the picture too. Hope this helps.
