Intresting flow question

[Canadian Man]

So let's say you have a powerhead like a MJ 1200.
Position it in a tank. Now when the powerhead is running, would it not make sense to count the flow comming out of the output nozzel as well as the flow comming through the intake?

This is probably a bad example and a better one may be a standard sump set up on a tank. The return is 600gph and the flow going into the overlfow box is 600 gph.. should the intake count for anything?

I realize that it's not as focused as the output of a pump but it is current and it should count for something. If you have 1000gph comming out of a pump you also have 1000gph going into the pump. RIGHT?

Let's hear your thoughts