If not a bog, what is it?
In about a five by five kiddie wading pool, I have had a variety of water plants growing, in containers, for a year or more. It has no drainage, has never been "cleaned" out. no drainage. Plants have grown well, and the water doesn't smell stagnant, putrid, or any other synonym. Dragonflies and damselflies love it.
Several things keep it from fitting the definition of a bog, but it must fit into some category? What might that be?