This varies according to each pond. If you have a lot of debris from over hanging trees, then you should clean it more regularly, using only partial water changes.
Now don’t get us wrong, a water feature is far from being a cure, there are health benefits to being near running water. Let’s look at a few of them.
Living in Australia, we enjoy a lot more sunshine than many other parts of the world, but even we can’t expect continually cloudless weather.