Turtles do a number on water lilies, eating them down to the pot level. That's why I eventually built a separate lily pool for growing lilies. It takes water from the bottom of the pond and serves as a settling tank for detritus. It also is isolated from the turtles. Now, I have my turtles and my water lilies. The only problem I have with it is goldfish eggs get sucked up into the lily pool where there are no predators and in the fall I have a bunch of young goldfish to get rid of.