One of the pond owners on Koi Keepers 5 stated that a koi pond should alway be at least 5000 gallons. The reason is that smaller bodies of water are more suspectible to problems from rapidly changing temps, ph...etc. There is probably a great deal of truth in that. At around 5,000 gallons we are also around the limits for what we should do to keep the pond to one bottom drain and one filter system.
Bottom line....try to get the pond a weeeee bit closer to 5000 gallons. You koi will greatly appreciate every gallon.
