I am still experimenting. For my tubs I use aspen without issue, but my tank doesn't hold the humidity well. I used coconut husk (the big chunks) and I liked it, but then I tired the eco earth (fine coco husk) and I hate it. It's messy and stinks. It also seems a bit too wet, then it dries out to dust. I love white carefresh, but it's pricey and while I find it a little better for holding humidity than aspen, it's not as good as the coco husk chunks. The carefresh is awesome for spot cleaning though, it's so easy to see the messes, even urates stand out because there is always a bit of yellow discoloration around them. I have never tried cypress mulch, it might be my next step for my terrarium.