I have a small pond and have had it for many years. Right now it has no fish so when I cleaned it out the other day I took out all the water and filled it back up. I have done this every year since having it without problems, even with the fish I would take most of the water out. Well two days after cleaning I noticed the new growth on my water lilies turning yellow and shriveled up. They were just sprouting out of pot and healthy looking when I took them out to clean so I'm thinking maybe it was something in the water? Just can't figure it out since I do it this way every year and have had the lilies for years, too. Any idea on what it could be and what I can do to save them? Thank you for any help.