Heat maintenance technology?
The bubbles are great, but then there's the "heater."  When they say their "heat maintenance technology keeps the water at the perfect temperature" you have to wonder what they consider the perfect temperature.  At times I thought I could perceive an attempt at heating--as the water got colder and colder.  Verdict:  You'll need more than 40 watts if you want decent heat.
Rating: 2 stars