This is dredging up an old controversy, but there was an Advanced Aquarist article comparing flow rates of popular power heads and there was some discrepancy between stated flow rates of Turbelle pumps and test results. Did Tunze ever change the way they advertise flow rates? I'm just wondering how stated flow rates compare between the 6150 and Vortech mp60, specifically. It looks like the 6150 has almost exactly half the flow. But, this is somewhat surprising to me because the mp60 uses 60 watts and the 6150 uses 50 watts. Is the vortech that much more efficient?