return pump noise when fully open

[ReefGeekCanada]

Hi

The set up is a Mag 12 with a 1" return that splits into a 1" return and a 3/4" loc line

There is lots of flow with the return valve (after the pump) fully open but I get an annoying sound.

If I partly close the return valve the pump just hums nicley. I don't want to reduce my circulation though...

What is causing that noise?

I'll will make a video to show what I mean.

cheers

[tootsiedaisy]

Tagging along mine does the same

[Agu]

Have you checked to see if there's a "whirlpool" forming by the pump intake. If it's cavitating (sucking air) it will make a nasty sound.

[jeeper xj]

i just had to add water to my sump to stop the cavitation, mine made a funny noise too.