just try and tell us how it works! :)

I'd be afraid of the mud smelling up the whole house.

I like the idea.

A suggestion if I may...

place your container in the aquarium and then fill the tank with pea gravel so that it is level with the rim of your container. At this point,top off the gravel layer with soil/moss,plantings,but keep the water under the soil layer and hopefully it should help to prevent the "mud" phenomenon that James describes above. additionally,..changing out the water will be easier this way as you could simply siphon directly from your little "pond" and the gravel around it will drain freely as opposed to soil and or moss.

Hope this helps! :)