Self Cleaning Koi Pond

Design your pond with straight walls and a sloping bottom. The vertical walls will not collect debris and they will also help keep predators out of the pond. Ideal water depth for a koi pond is 3 to 4 feet. The bottom should slope to centralized bottom drains. These drains will take the dirty water to your filter. Cement ponds can be vertical. Liner ponds may need an angled wall in order to prevent the soil from caving in. The liner wall can be a vertical wall for the first 18 to 24 inches depeding on the stability of your soil. The wall can then angle towards the floor to make up the additional depth needed to achieve 3 to 4 feet.



If you want aquatic plants you may add planter shelves in various artistic locations. Make the shelves at least 18 inches wide so the plant pots will be stable. The shelves need to be about 12 inches deep for bog type plants. This will put about 2 to 4 inches of water above the pot. Lilies need to be in 18 to 24 inches of water.

Remember however, that an 18" or less plant shelf will also be a place where predators like racoons and herons can stand. So keep these shallow shelves to minimum areas whereby if a predator does stand on it he cannot walk around the entire perimeter of the pond. Put these shelves in limited areas that will compliment the look of the pond but not create a walking zone for predators.


The diagram below shows a top view of different shapes that can be considered self cleaning. Notice the placement of the jets. The jets are positioned to flow the water along the perimeter of the pond walls. The jets do not point out to the middle like a swimming pool. The jets flow follows the contour of the pond walls and creates a toilet bowl effect funneling debris to the center drains.

Source:
http://www.lagunakoi.com/Filtration-Designs-c-9.html