An expensive and absolutely useless item! It couldn't even suck up surface debris, let alone the silt at the bottom of the pond. What little does enter the cylinder soon clogs because debris gets stuck in the 90 degree bend to the waste bag. I was therefore having to dismantle the pump after every three or four strokes to clear it out. However, the plastic threads keep binding, so dismantling is not a quick job and although I'd only tried the pump for some ten minutes, that was sufficient to convince me that the thing would never work properly. Thereafter, I reverted to my nets which did a far better job.
Purchasing this pump was an expensive mistake. It didn't even come with any instructions and is best avoided.