I'm using coco husk right now which is working fine for me, but I'm considering trying something a little more natural. My first choice is a mix of play sand and sterilised topsoil, more soil than sand to avoid eye problems, would that be safe for a BP? I know it's fine for corns and I'm not sure why it would be any different for them, but I just wanna be sure :) I'm not going for bioactive (at least not for a while). I'll probably add some sphagnum moss in with it too.