i wouldn't recommend indoor/outdoor carpet as a substrate. it holds zero humidity and they can't burrow into it. in fact, i've heard of tegus getting their toes caught in the carpet and getting their nails yanked out.
i go with a mix 0f 50% screened topsoil, 25% play sand and 25% fine vermiculite. you just pour water in to keep humidity up.
topsoil and vermiculite are dirt cheap (HA!) while the play sand is a little more expensive.
i gave my tegus about eight inches of that and they love it! they burrow like crazy, sometimes they even do it right up against the glass and i can see into their tunnel system!
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if nothing else, i at least amuse myself!


