it would be easier to draw it out than enplane it.
There are 2 water discharges into the system
1 is the waterfall
2nd is just to the left of where the waterfall drops into the pond.
both can be independently controlled in the pump pit.
water has 2 ways of exiting the main pond.
1. under the waterfall are 3 bottom drains.
2nd is the spillway leading to the preformed pond aka bio filter.
on the bottom of the preformed pond is a grid of pvc pipes covered with rock, stone, and pebbles, this network of pipes also leads to the pump and can be independently controlled.
Hope this helps
At a later point in time I will do a write up with drawings explaning what, where and why.