I use cheap astro-turf (no backing). The "grass stands about 1/4" high. I like it because it lays flat and raises the animals off the floor and completely away from the excessively hot under tank heater. The problem is that it is easily shredded (by the snapper) and in any case, loose peices may be ingested with food. I have not used "reptile substrate" and don't know if it is the same material. Either way, even though it's "cheap" and I vaccuum it to remove dried mess, it does'nt get changed often (enough). As good a reason as any not to use it. Notwithstanding, I'm always on the lookout for a better solution - easy clean, not ingestable, non-abrasive, mould resistant, etc. I know, "put 'im back where I got 'im"!