===== Koi Pond measurements ===== * 12 gallons of water equals 1/2 inch depth * Our pail holds approx 4 gals * It takes 2 minutes to drain 1 inch of water using the pump * When the pond was down to 10 inches, this is approx 240 gallons. Adding 12 gals is 5% more. Recommended is not to add more than 5% every 2 days.