A bit about the filter hardware/design.
Mechanical separation is handled by this work of genius. Chinese made, but of Dutch design (Estrad BV). It removes suspended waste like koi poop. Automatically. No back breaking and time consuming work cleaning filter brushes and japanese mat. The waste is removed from the water stream. It doesn't get a chance to decay and release more ammonia into the pond.
There is a small settlement chamber preceding this filter to drop heavy stuff like pebbles out of the water stream and catch leaves.
Mechanically cleaned water is pumped to a built to order shower from Florida-based Deepwater Koi. This is designed for 3cf of MP2C. The pressurised manifold ensures even distribution of water across all the MP2C.
This system needs almost no maintenance, being fed by water filtered to under 50 micron.
And that is all... A simple 2-stage filter design for ease of maintenance and high performance.