Bubbles mystery?

[Poollover4]

Good evening
I hope some can give me an advice about bubbles in return jets of the spa

I get consistent bubbles from one of my spa jets and occasionally the one next to it without air blower being on. Is that normal? My blower is old and I am thinking may be check valve going bad. It does work and makes big bubbles come out from all jets but there are still bubbles when it is off. What would faulty blower check valve cause?
Thanks

 

[ajw22]

Blower check valve keeps water from going up the air pipe into the blower. Not from keeping air going down the pipe.

Are those rogue bubbles causing a problem?