Correct I am a koi keeper, a koi dose not have a stomach as such so the more u feed about 2 hours later wast is produced at an amazimg rare, if ur pond suplyer told u that the filter box and pump will suit the size of ur pond, where koi are involved then you need to half it or double the size of ur filtration bio bed and to keep your koi trim and healthy water flow and aireation, as what is a stream filter bed, is where the water flows over rocks pebles, etc this supports all the creapy crawles water movment and areatiom just the same as a natural stream plant life etc, as what I have to do is try to recreate this system using plastic boxes k1 and air pumps,