One of my 4 return jets has many tiny bubbles in its stream... You can see them only when you get really close to it, or at night, when you turn the light right next to it on. The other 3 don't appear to have any.
I have a setup with one pump that's driving 3 return pipes -- one for a waterfall feature, one for a bubbler, and the third one is common for all 4 jets.
What could be the cause of it? If all the jets had it, I could blame the pump/filter, but since it's only one of them, does it mean it's a crack in the pipe after the 4 jets are split? If so, I would expect to have a leak, but I don't think I have any unexplained water loss (I have to add about 2 inches every week or so, but it's 100 degrees and sunny all day long, and the pool is used just about every day).