Why is the 9015 rated to skim a larger volume of water than the 9010? Both units have the same water throughput 317gph, air capacity 171gph, and power consumption 21-watts (which I assume means they are using the same pump). does the 2 inch larger reaction chamber on the 9015 really allow it to skim 132 more gallons of water volume as effectively as the 9010 (this is of course with all variable being equal) or am i missing something.