I would NEVER submerge this plant.
![nono {nono}](https://www.worldwidewatergardeners.org/forum/Smileys/smilies_smf/nono.gif)
Maybe stick it in the crevices of waterfall rocks, off to the side so it doesn't get a lot of splash, and
only the roots in the water.
And make sure you save a piece to pot up properly planted, in case all the pond planted ones rot.
This plant can grow in very arid conditions.
We saw it on our honeymoon in Eleuthera growing from rock crevices in drystack walls made up of coral rock. I took a few pieces home, and grew them in an 8" pot on my patio for years...pot was CRAMMED with the plant. I allowed the pot to get pretty darn dry before I watered it again on many occasions.
I would not expect it to do anything but rot if submerged.
By the way, the proper botanical name for it is:
Rhoeo spathacea, syn. Tradescantia discolor, syn. Rhoeo discolorAka Moses in a Boat, Moses in a Basket...
http://davesgarden.com/pf/go/650/