I would like to build a really small (~1.5 x 1.5 m2) alpine garden with a water stream in my garden. There is already a plastic pond there, 0.35 m deep and 0.6 m in diameter, from the previous owners, which I am actually going to cover. I have a baby daughter and don't want her to fall into water one day. I need to select the correct pump for the project.
I've read that ideally I should pump the complete volume of water each hour. The pond volume is just below 100 l, and I was unable to find an outdoor pump with the flow rating below roughly 400 l/h. So I am wondering:
Can a pump be actually too powerful for a given task (not in the sense of wasting money, but in terms of creating a ridiculously powerful flow, spitting water all around the place etc?
Can I somehow regulate the actual flow once the pump is in the pond, to make the stream look natural?
The pump I have found is rated for the maximum height of 0.7 m. Can I rely on this value if I want the alpine garden to be 0.6 m high (from the water level), or do I need some safety factor and thus an even more powerful pump?