This pump looked too good to be true when I saw it on Amazon.
The additional technical details appeared to say it could handle a head ("maximum immersed depth") of 9 m, it was less than half the price of other pumps I'd been looking at, and the quality promised to be good because it was from a reputable German manufacturer.
Well, you know what they say about things that look too good to be true.
When the pump arrived, the literature with it said it could only handle a maximum head of 6m and that it wasn't suitable for continuous operation - something not mentioned in Amazon's sales blurb.
As a result, the pump wasn't suitable for my application - pumping water continuously around a cascade, with a head of about 8m.
I almost returned the pump and then realised I could swap it with another, higher spec pump, in my other rainwater harvesting system and I'd be okay.
I've done this and the pump works fine.
It isn't anything like as powerful as the pump driving my cascade, but to quote another adage, you get what you pay for.