For over 2 years I had a cheap kiddie pool for 2 southern musk turtles who were kept in the yard (Florida). The pool was a cheap and gaudy kiddie pool casper cartoons. I am going back 20 yrs when I was a kid
I had chicken wire screen over the top ,it was filled half way with water.
With some haul out driftwood in the middle of it.
I would put in a pump attached to 2 inch type siphon tube and drain half the water each week and refill it with hose.
It never leaked never had the slightest problem . The key was the haul out area in middle of pond so they didnt try to climb out . They did very well outside.
However the ponds the previous post talks about are much better built than any kiddie pool granted not as much room unless you buy the very large types.