A nice big word which explains why your (my) pump stops working in the middle of the night for no apparent reason. I attribute mine to the fact that my pump placement is about 1 foot above water level which is not ideal for my pump. Cavitation occurs for many reasons but the main ones I seem to have are air accumulation on the intake side, disruption of water flow from Frogs entering my bottom drain, and I just learned I have an elbow too close to the inlet.
Note to self: When I move the pump, put it below waterline with pipe running straight into it.
Here is a resource for other Cavitation like problems for pond pumps.
