Pond Lily

Koi Pond Site Layout

So you are ready to build a koi pond but there are several things you have to consider before starting. What are the essentials of a successful koi pond? Koi sold at pet stores are anywhere from 4 to 16 inches, but they will grow to 30 inches or more. This means that a koi pond will have to be larger than other water garden ponds. It should handle a flow rate of at least 3,000 gallons per hour with a good skimmer. The koi pond also needs a shallow high flow area like a stream and also a large deep pool area of 24 to 30 inches deep. I would recommend 30 inches as the ideal maximum depth. Anything deeper than 24 inches will insure koi will survive the coldest winter but 30 inches will give the koi a place to go to escape the worst predator the blue heron. A waterfall is a nice feature to any koi pond adding to the the oxygenation of the water, but is not an essential element. A back yard with a slope of 4 feet or more makes it an ideal candidate for a waterfall or stream. Having a completely flat yard would require building a berm in order to incorporate a waterfall. That's not as big a challenge as you might think. After all you have to do something with the dirt and rocks when you dig out the pond. Planting tall shrubs and trees at the sides and behind the berm will make it look more natural.

How Big To Make The Koi Pond

We have already determined that we need a flow rate of at least 3,000 gallons per hour. So how big should you make the pond? Leaving out the shallow area let's calculate the gallon capacity of the pond. To do this take the depth of 30 inches (2.5 ft) times the width of 8 feet times the length of 16 feet. 2.5 x 8 x 16 = 320 cubic feet. Multiply the cubic feet by 7.5 to get the gallons. 7.5 x 320 = 2,400 gallons. We could get more detailed, but the general idea is to turn the water over about 1 to 1.5 times per hour. Adding in the shallow areas, the stream, and the waterfall is usually not significant enough to calculate in the overall formula. Click here to use our FREE pond liner size calculator.

Trees and Utility Lines

Koi ponds tend to do better in full sun. Water lilies and many water plants need plenty of sun to reach their full potential. Choose an area the gets at least 4 hours of full sun. Digging to close to a tree will damage the surface roots and may end up killing the tree. Keeping the pond away from trees means fewer leaves ending up in the pond in the fall.

Many utility lines are run underground and before you start digging you should make sure where these lines are buried. Most cities will come out and mark where these lines are at no cost. You also may want to check with local requirements for having an outdoor koi pond. They may require a fence to keep small children from drowning in your pond. I would always recommend this. The liability of a child drowning in your pond falls on you.