I've never made a pond before, but I want to for my babies, so I have to ask how you did the water feature? How deep is it? How do you keep the water fresh -- do you "flush" it periodically? Details needed for this [construction-]challenged Turtle Mom, please!

Right now I have an 18" plastic flower pot saucer. I lined & sloped the sides with quikcrete (my babies are still small enough, but growing!!). I have a garden dripper going to keep it full, and I flush it with a water hose every day. But with 8 growing children, I need to expand the watering hole!