One of the most interesting studies done in recent years was conducted by Kasco Marine on their Robust Aire fine bubble diffusers. They used an independent testing lab, with the ultimate goal of finding a more efficient and effective diffuser design, compared to other leading systems on the market.
Eventually what they came up with was a diffuser that proved to be anywhere from 10 to 40 percent more efficient, meaning for the same amount of horsepower in a pump, it could produce higher cfm's of air output into the water...which will generally improve turn over rates and oxygenation of a pond system. An added benefit was they found the new diffusers produced less back pressure on the pump, which can help to extend the working life of the pump while reducing the frequency of necessary maintenance.
If you'd like to look at this study and it's results in more depth be sure to visit the link below.