I have been using a mixture of fir and sphagnum peat moss, and after researching this at arachnoboards, it appears fir is toxic to tarantulas. (It's also not the easiest to see cricket remains on). I haven't seen my H. maculata on the substrate at all, and at night she's very active, roaming the sides, top and cork bark back. I needed to perform some maintenance anyway (bug juice slung all over the place), so I removed the fir mixture. What substrate do you recommend for an arboreal set up?