What is this piece on jet tub? Is it important?

This piece came apart in the section I have circled on a new whirlpool tub install. Where it continues up under the lip of the tub it goes to nothing it is just capped. What is this for? just a vent? The tub is already in a bed of mud and screwed in place and would be a nightmare to remove and I'm hoping it wont be necessary to tear out and fix if this is just some sort of vent? thoughts?
Also it is on the back side of tub with 3 walls surrounding it. It's not the side I took a picture of so like I said big deal to tear back out.

It looks like it's were the air is put into the jets. There should be a adjusting nob on the tub.

johnjh2o said:

It looks like it's were the air is put into the jets. There should be a adjusting nob on the tub.

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can you elaborate by what you mean air put into the jets? this is in the back of the tub in the center against the wall there is no way to get to it to adjust anything ever even through the access panel in the front it would not be possible ever. Do I have a problem where I would need to tear out the tub if that separated at the y on the single inlet side? It looks as though no water runs through it?

It should be connected to the top of the tub with a nob to adjust the flow of air into the jets.

contact he Manufacturer and ask them