knocking noise when jets are on

[Jostudly]

I would like to know why I get a knocking or thumping noise under the tub when the jets are on high. Is this normal?

[av8r]

Do you have jets that include motion?  circular, figure 8, etc?  If so, it could be those.  Try holding them still and listen for the noise.

[Jostudly]

I do have those jets but the knocking is coming from underneath the tub.

[av8r]

Water is a good conductor of sound (better than air) so you may think it's coming from there.  Try what I'm suggesting which will either rule out or confirm.  Another option could be air in the plumbing as it can sound like a knocking noise.  Hard to say without hearing it.  Shoot some video and post it on youtube.

[Jostudly]

My dealer says it is normal to hear this noise when the jets are on as the water is circulating very fast. It is not a constant noise but intermittent. I close the jets and still get the noise. If there is air in the pipes how do i fix that?

[av8r]

My dealer says it is normal to hear this noise when the jets are on as the water is circulating very fast. It is not a constant noise but intermittent. I close the jets and still get the noise. If there is air in the pipes how do i fix that?

You don't fix it.  It's normal to some degree.

[Jostudly]

okay did not think it was normal

[av8r]

okay did not think it was normal

without hearing it...hard to say for sure.  It's like when my wife comes in and says the car is making a funny noise.  Kinda need to hear it for myself.

[wmccall]

I do have those jets but the knocking is coming from underneath the tub.

I had a similar thing happen many years ago with my previous tub. The pump motor had 2 loose mounting bolts on one side.   On high the pump generates more torque and would make a thumping type noise till I tightened it down.