i just built my pair of leopard tortoises a new indoor pen and im looking to see what most people are using for substrate, ive used newspapers for the last 12 yrs but im sick of it when they poop if im not home they walk around in it all day. ive seen them on sand, cypress mulch, rabbit pellets, and hay wich looks good but im worried about it under 100 watt bulbs. what does everyone use????