Intresting flow question

[Aquattro]

Jon, I don't think you can count the flow going into the pump. Even on the stream, there is very little water movement until it gets within 1/4" of the intake. In a ratio of water movement out compared to in, the in would become insignificant.
To get an idea of the flow, drop some spirulina flake near the bottom of the PH....it won't do much until it's almost in the pump.