Hi! I have 7 juvenile green and gold bell frogs (I know it's a lot to have, but they're essentially rescues - they were taken from awful conditions in a closing-down petshop as tadpoles.) They're currently very small and are living in an old fish tank with a less-than-ideal setup (substrate is boiled wandering jew leaves over sterilized clay soil), but they will definitely outgrow it as they age. The frogs will grow up to be 6-8 cm in length average.

- We intend to build a terrarium from scratch and thus have control over the dimensions. The largest size easily accomodated by where they currently are is 175cm long x 30cm wide x 40cm high, or about 55 gallons. The height can be increased, as can the other dimensions if the tank is moved somewhere else. Is this sufficient? Is the lack of width okay if made up for by the length? Should height be increased? They are tree frogs, but most sources I've found have suggested they don't climb much, although mine often stick to the glass/climb up into the corners of their current tank while hunting (houseflies and fruitflies.)

- Substrate. I read that white's tree frog shouldn't be kept on a loose substrate as they can ingest it accidentally when lunging for prey. As far as I can tell, mine feed in a similar fashion - I intend to have a lot of the land area taken up by plants and large, flat, smooth rocks, but would it be safe to use (sterilized) soil as substrate if the remaining area was covered with something: ex. leaflitter, groundcover plant, living moss? If so, where might I be able to find appropriate live moss, and what are some safe groundcover-type plants? I've had an awful time trying to find any.

- overall, my ideal plan for the viv is to have a drainage layer of aquarium gravel, soil above that, and then rocks/plants/groundcover above that again, with water either in a dish or in the base of the tank at one end, held back from the soil by a bank of (insert unresearched cement-like material here) made watertight (or near enough) and filled with emergent plants. How does that sound, functionally and safety-wise?

- I am also considering having the entire base of the tank be filled with water with a LOT of emergent plants/large stones and branches. This would avoid substrate altogether - but might be harder to clean? Which is better? What problems are there with each?

Thank you so much for your time!