Sure, it sounds good, but the authors have forgotten a few things:
1) Water rising from heat is called "Convection" but is only one of 3 ways heat is transmitted. The other two are "Conduction" and "Radiation". They are all equally important.
2) Cleaning the pool IS more important than heating it--sanitation is critical. But as someone else pointed out, the circulation is very powerful and mixes the water very rapidly. While boiling a pot of water makes the most sense to heat it from the bottom, if you have a mixer going, then heating it from any direction should be about the same.
3) I solar-heat and circulate my water all the time and the bottom of the pool is rarely much cooler than the higher water. I don't have a "thermocline", which thein author's system pre-supposes.
4) When using a CLEAR solar cover, sunlight penetrates all the way to the bottom of the pool, heating from the bottom as well.
5) The claims of energy efficiency are MEANINGLESS to a person with effective solar heating. My heat is already free--if my pool is warm enough, why do I need to increase that.
6) The increased efficiency claim is undocumented.