Aww....Your ducks look fabulous!
I did slot of research re a pool before getting ducks for the first time in January this year.I started out with a preformed pool at first and spent slot of time digging it in and landscaping around it. The reason I chose a smallish pond was because I thought easier and cheaper to empty out and refill!
No no no no......
It took only a few days to realize that I needed to go bigger....
For one a small pool really does get stinky even after just minutes of emptying and refilling. Two is that, although my ducks were using it all the time they weren't really playing in it.
So several months later I've almost finished the final big pond set up, complete with landscaping, duck decking, diving platforms, filtration (doesn't keep water clean but helps a bit for sure),waterfall, pool layered steps to get in and out and small stepping stone in the middle that they can rest on and groom.
They love it.......
So, we'll done with the larger pool, what a bargain and you'll see them playing about much much more with the larger water space.