Loud sucking sound from filter

[Starman]

I have a new Maax spa model 781. There is a vortex in the filter area and it has a round pre-filter . Occasionally there is a loud sucking sound.
Is this normal?

thanks

[Jacuzzi Jim]

 Yes, sometimes worse with low water level.  Some 200 series Jacuzzi's would do it as well, I usually suggested removing the skimmer that bobs up and down if it's annoying when you are in the spa.

[Starman]

No bobbing skimmer here only the weir door ,I could remove the prefilter

[The Wizard of Spas]

Keep water level higher and problem likely goes away.  Weir door removal, as noted, reduces/eliminates it too.