Hi,

I'm in the process of planning out my first "terrarium" (I'm not sure if that's technically what this would be called). Essentially I want it to contain a fish pond (no more than 6" deep) and cork/cypress walls to mount some orchids. The pond is going to cover about 70% of the base of the tank (corner unit about 2' on each of the three sides, 32" tall).

I was hoping to use that expanding foam insulation to fill the bottom of the tank, carve out the pond and then silicone river rock to the surface. The rest of the base that is not submurged would be coaco-bedding siliconed right to the foam. On top of this I intend to grow some kyoto moss. A mixture of capilary action from the coaco bedding and using a mister from above would keep everything moist. This however cuts out one of the major components of all terrariums....the drainage layers.

I figure with this setup I can still grow some water plants in the pond and mount my orchids to the walls. Because of the carving of the foam, any excess moisture would drain down into the pond. It would contain a waterfall feature, used to move and filter the pond water. Is this idea doomed to failure? Are there any epiphitic type ferns or other plants I could still grow on the part of the base that remains above water?

Thanks,

Tyler