Hey, need some help. Just finished an arboreal cage for my giant day (27*28.5*47) and want to put potted plants in it. My question is what soil can I use to repot these plants in? Preferably one that is widely available and not too expensive. I will have a waterfall and rain drip system in it and am concerned about the toxicity of some of the potting soil additives leeching into the water supply. Any ideas? Thanx.