I have used virtually every power head that has come out in the last 13 years. Only the gyre has managed to strip coral flesh off my large SPS colonies at over two feet away from the pump. It's just as loud as the mp40, but at least the mp40 has an excuse that the noise generating part is outside of the tank, making it more likely to be heard. The gyre is submerged and is just as noisy. Compare this to the Tunzes, Jebaos, korallias, maxijets with algae free mods, and the racket the gyre makes is inexcusable, because all the other submerged pumps listed above are virtually silent. Gyre looks impressive in newbie tanks that have hardly any stock, little live rock, etc. but when you put it on a ten year old tank with much live rock and large, mature colonies like mine, you'll quickly see how un impressive and harmful it really is to the livestock. I also doubt it will last ten+ years, as my Ecotech and Tunze pumps have.