Nice. Good idea using those panels. I have them for my guinea pig cages and floor pen. Never thought of using them that way.
Just a suggestion though. They look a bit small, so maybe you want to put something in the pool to hep them get out easily. We have one of those pools too, and even my adult Runners and my Mallard can have trouble getting out of it. They can either get hurt struggling, or if they cannot get out, drown because they just get too waterlogged and exhausted. Also, the blocks on the side might be better made into "steps", they look rather steep.