i have a pond 3 feet deep, 10 feet by 10 feet with a canister filter. i live in ontario, and i dont have any problems with how clean the pond is. the question is my hardy water lily is doing very well, but i am concerned its root system may be crowding the fish. it was divided 4 years ago, and i have about 15 goldfish. if i almost empty the pond to divided the lily and see what its like down there, will i disturb the frogs that live there? do i even need to divide the lily. other than the filtration, and s winter heater the pond mostly takes care of itself