It's an eye opener as he explains the differences in stocking density between different aquacultural situations and shows graphically how the increasing size of your fish dramatically increases the burden on the filter. Unfortunately, the answers to these seemingly simple questions aren't nearly so simple. Stocking density is the leading parameter that affects all other design decisions.
Lets take a look at that first.
The stocking density of a pond can be measured several ways. To the novice, it is simply the number of fish in the pond. Since the size of individual Koi and the nature of individual ponds vary so drastically, I would propose that a more useful measure of stocking density is gallons of water per pound of Koi. Lets look at the characteristics of each of these situations. Require great quantities of labor, energy, and technology.