HI --- My tub has water jets and the air bubbles . I love the air bubbles the most . I have not had the water cool off and my tub time is usually about 3/4 of an hour . My tub has two motors , one for each. I think it is a bit of a myth that the air will cool off the water . Not so , if that is what you are worried about .

We've had an air tub for a little over 10 years now. I'm happy to say we've had ZERO problems.

Like lefty, the water does cool off naturally - although I don't think mine lasts for a full 3/4 hour. When it gets cooler than I want, I just add a bit more hot water. At the time we purchased ours I don't think in-line heaters were available. If I were buying again, I'd probably add a heater if available.

I love that I can use bath oils or whatever. I love that water doesn't recirculate in the pipes. I love the gentle massage vs jacuzzi jets. I pretty much love everything about it and would do another air tub tomorrow if I moved to a house without one.