In my experiance just sand alone sux as a substrate. Now a deep layer of good old fashion moist dirt or a 50/50 dirt/sand mix works amazingly well for Leos. It will naturaly break down most of their waste making clean up a breeze, shedding issues become non existent and from what Ive seen females who nest naturaly tend to rebound amazingly fast between clutches.
Hmmm but what about slate rock? I used to have white cermic alike tile, I put it on warm side, it became too hot and I had to stack it about 5 blocks of cermic tile. It's getting too much pressure on my tank's wire of heat pad.
You can get light dimmers at any home depot or rona that your heat pad will plug in to for about $10 (in canada) I've used them for a while now no problems
I wrote an article about the various substrates and the arguments for and against sand. Personally, I would not use sand but, read the article and see what you think. click here
I use coco fiber and my 2 females eat and poop it regularly, so it is safe and natural looking. You buy it in bricks and soak it, let it dry and then use it, also you may want to get a rheostat for your UTH so you can control the temp. The coco fiber is also good because they can dig in it and also where their moist hide is, just spray the coco fiber thats in the hide when you see that they're shedding.
Heres my 20g long that I have 2 females in on coco fiber for almost 2 years now.