I have a large terrarium with about 4 inches of water in the bottom, circulated by a submersible pump. Mini milk crate baskets sit in the water to support a plastic grid up above the water that potted plants sit on. Moss grows on the grid.
I have Neps, a Ceph, and Sundews in there. The critters in there are about 50 guppies, a fire bellied toad, a salamander, and an algae eater - since it's impossible to clean the algae that forms below the grid.
The toad hops all around in there, on top, and swims in the water too, translocates plants and seedlings sometimes. The salamander is seldom seen - you never know where it will pop up. One time he poked his little head out from under the rosette of many N. ampullaria pitchers - but I had no film to capture the moment. The critters have been in there over two years - never had to rescue them from any of the pitchers. I was thinking of maybe adding a baby crayfish or something to help cut down the ever exploding guppy population.
I water the big Neps in there once a week, then the same day change out the yellowed water in the bottom.
WildBill