I'm not Nedra, but thought you might like to see this page on
repotting water lilies.

and fertilizer part (I think G), but what about the old pot? Should I try
to move it in one piece, or should I wash the dirt out, exposing the tubers,
and then transplant those to the larger pot? What's the process???

http://loricase.com/ponds/repot.html

Lori