[kingkong]

Hi Reg, How about a freshly cycled bio-filter can handle 1 pound of koi per 150 to 300 gallons of pond, or 1 pound per 1 ton.
10 gal H2O per pound of koi produces 1ppm of NH4 (Amonia) 2 hrs.
5o gal H2O per pound of koi produces 1 ppm of NH4 10 hrs.