Water pump pulsing

[Wavery]

Actually, it works even if the "Rubber" hose is full of water. It's the slight flexing of the hose. If you watch the hose coil, you can see it try to straighten under pressure then relax when the pump is off.

I did this many years ago on my yacht. The pump was very noisy without it and when I installed the hose, the noise went away.