Re: Water feature critters!
I have a small water feature in my A. dorsalis vivarium. These are frogs that normally live on the water's edge, so quite different from your frogs. Regardless I'll share my experience with the water feature.
There are snails and Asellus aquaticus in the water feature to help manage any waste that drops in there (mainly flies and frog poo). There is also a sizeable population of water fleas and copepods in there. Plants-wise I keep Laevigatum limnobium and Cryptocorynes in there to absorb and recycle any Nitrogen and other nutrients that get released by the snails and whatnot. The Cryptocorynes are also for egg deposition for the frogs. Mostly I just have to remove some of the L. limnobium every two months as they tend to start overcrowding the water after some time.
So far this has worked very well for me, although I have to admit that the setup hasn't been running for very long yet.
Currently keeping Dendrobates auratus "panama special", Mantella baroni and Afrixalus dorsalis