ExoTerra makes 2 enclosures that I like but each is a different size. One is 18x18x12. The other is 18x24x18, which is about $50 more but otherwise very similar. In both cases, there's ample room for a deeper layer of substrate. Overalll construction between both is very similar. A T stirmi might even get to 11" DLS, but 9" DLS is more common from what info I've been able to find.