Questions are good. That's how you learn the pond varies in depth, from 2 - 4 inches. The frogs have so far completely avoided the pond side of the tank. They like to hang out near the Buddha statue. I've got a piece of plexiglass to keep anything out from underneath my land section and a couple pieces of mopani wood going from the pond onto the land portion so in case someone falls in, they can hopefully climb out. So far, I've got springtails in the tank, but every once in a while, I add more. I think they are sustaining in the tank, but I add more to offset the ones the froggies eat. On friday, when I get paid, I will be ordering isopods from Josh's frogs so I can seed with that as well.