I disagree. You can make the substrate itself bioactive if you so it correctly. No need for plants or anything for the tegu to destroy. You could even just dig dirt up from your backyard if it's pesticide/debris free and it would have the micro-organisms to be bioactive.Are you wanting a bio-active setup for your tegu? Because they're almost impossible to maintain with tegus because they're so destructive. If not I wouldn't bother.