multilevel duck pond

[mat]

Wanting to make a small duck pond using a water pump, plants, and snails. Saw a variety of opinions and ideas online. I considered idea of a multilevel pond with the plants and snails on top level (keeping ducks out of top level) and water flowing down to second level for ducks. The pump would circulate water back to top level from a tube a few inches below surface of second level to keep away from inevitable muck on bottom. Does anyone think this would work to preserve plants and snails from possible problems, clean the water, and cut down on cleaning the muck from bottom level?

 

[chickens really]

The Ducks will eat the snails like candy and possibly the plants too....I use kiddie pools way simpler ....