No expert here are you all talking about exchange of gas or how much O2 you can create? What is the point (just curious) is raising fish in a tank that complex? Like I said I am ignorant you are all the ones that do this to high degrees but the O2 thing..well I work with that allot making ACT and the amount of oxygen agitation that is created when I use a high power regenerative blower seems to do best when it is introduced lower in the tank and air bubbles rise up and out. Make sense? Just asking is all