i can give you some tips for growing tropicals, but I have some caveats... I live in Hawaii, so sun is not a problem for me. I grow my plants in containers that are no larger then 50 gallons. I have multiple plants per container, usually 2-3.
I plant the water lilies in standard gardening pots. I put a couple layers of newspaper on the bottom and fill with topsoil being sure not to cover the crown or growing point. I put a layer of Special Kitty brand kitty litter on the soil to keep in from coming out of the pot. That stuff is basically crushed clay. It's sold at Wal-Mart in a red paper bag. It's 25 lbs. per bag. But, if you don't want to use this, any type of heavy media will work. Like Carolyn said, you can use stuff like the kitty litter as the planting material. I don't use it because there are no nutrients in it and I'm afraid that it's so porous, that pushing fertilizer into it will eventually lead to it leaching into the water.
I use pondtabbs at one tablet per gallon of media per month. I like this because it allows me to plant larger tropicals in smaller pots. Once they get rootbound, the tablet is harder to push in. Once it too hard to push in, I repot.
My plants are no more then 8-12 inches under the water and I have no problems.
I hope that I didn't miss anything and that this helps.
I repot anytime because sun isn't an issue. Because of this, I don't know how to overwinter tubers.
