As you can see here, to create a perfect waterfeature, even a small one, attention to detail at the digging stage is vital. So many pools are ruined because ledges were dug to the wrong levels or even not created at all. Water depths and ledges are vital for the balance of the pool and also for the disguising of the liner.
ALL YOU COULD EVER NEED TO KNOW AND MORE IS IN: 'HOW TO DIY EVERYTHING'.