Couldn't disagree with you more. Even in areas of the ocean where current is mild it would still equate in many cases to over 30 times turnover. I was making a broad generalization that would accomodate all types of corals when I stated the 30 times per hour. For an SPS only tank it would be wise to shoot for a 60 times per hour turnover rate. Keep in mind that this should not done by one powerhead, or one nozzle on a return from a sump pump, but instead a larger amount of nozzles, so you aren't going to be tearing corals "right off their rock/skeleton". If you are wondering more about flow recommendations I woud direct you to the Book of Coral Propogation by Anthony Calfo, or Anthony Calfo's forum on ReefCentral.com. I know that if you have been used to the really low flow turn over in freshwater tanks, the recommended turnover rates for reef tanks can be jaw dropping.