Well you certainly aren't overstocked!
There are a number of possible things to think about with respect to water movement. First, and you may know this, there is a rule of thumb with filtration, to get you started, of how many complete turnovers of the volume of your tank water per hour - the rough rule is 5. You also hear this stated as 4 to 6 turnovers per hour. So for a 75G tank, the rule would say 375G per hour for your turnover rate.
Fishkeepers generally increase this if they have especially messy fish which eat more than average and/or are large and they generally back off of this some if they are more interested in planted tanks and having plants that don't like too much water movement. Water movement disturbing rooted plants can be somewhat controlled by the aiming of spray bars in such a way as to minimize plant movement.
Another thing to think about is whether there are spots in a large tank where currents don't reach. This can be a good or bad thing in a minor way, but just thought I'd mention it as something to think about.
Finally, by far the most important aspect is that of surface movement. This was well covered by Scotty above. Minor adjustments of a spray bar output from a pump can make a significant improvement in surface agitation and improvement in gas exchange for the water. I was one of those who, years ago when I first practiced the hobby, erroneously thought that airstone bubbles significantly increased surface area. In fact they don't and its really the dirsturbing of the surface they do that is significant as far as gas exchange is concerned. Thus a spray bar doing that is also very significant and if you don't want a bubbler disturbing the peace of your tank, there is not a lot of reason to have one in an established tank. That's not to say they are not a lot of fun of course.
~~waterdrop~~
