Im working on making a humid hide/humid burrow for my uro because on the deer fern farms website they recomend it. They said to use a tupperware (or rubbermaid - whatever) and connect tubing to it to make a tunnel and use a sand/potting soil mixture. I have everything except the potting soil nd i am wondering what TYPE of potting soil to use. I went to home depot but everything had fertilizers or was specially formulated and im worried about using something with chemicals. What do you guys use in your hides? What type of potting soil should i use? thanks!