How to Build a Wooden Koi Holding Tank

Written by nina feng
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How to Build a Wooden Koi Holding Tank
Koi can be a beautiful addition to your back yard. (contented koi image by Geoff Hobbs from

A wooden koi holding tank holds koi fish -- Japanese-bred ornamental carp -- and they can be very aesthetically pleasing in your backyard or outdoors as part of the landscaping. You can build your own water tank; just decide how large you would like it and what type of wood you will use. Acquire wood from your local lumberyard and home improvement store, and purchase koi online or from local fish nurseries.

Skill level:

Things you need

  • 1 inch by 4 inch cedar planks
  • Electric drill
  • Pond sealant
  • Sealant gun
  • PVC pond liner
  • 3-inch nails
  • Scissors
  • Hose

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  1. 1

    Locate the spot for the koi tank, preferably over a concrete, flat surface. Then place two planks of wood parallel to each other on the ground with about a plank's length of space between them. Now place two more planks on top of them, spaced the same, and perpendicular to the previous planks to create a square.

  2. 2

    Drill two nails into the end of each plank on top to secure the base structure. Continue stacking and nailing planks in this manner, much like how a log house is created, with every layer of planks perpendicular to the one below it. Layer the planks until the structure is as tall as you desire.

  3. 3

    Apply a line of pond sealant, using the sealant gun, around the bottom edge of the tank. Squeeze a line along the floor on the inner side of the tank, and don't forget to apply the sealant along all the tank's joints as well.

  4. 4

    Line the tank with pond liner, shaking out the sheet. Step inside and work the liner into the tank so it fits snugly into corners. The liner should flow over the top edges of the tank.

  5. 5

    Turn on the garden hose and fill the tank with water. The water should push the liner down so it forms to the tank.

  6. 6

    Pull the edges of the liner gently towards you, and use scissors to neatly cut it so it fits over the lip of the tank.

  7. 7

    Place another layer of planks on top of the liner so it's hidden beneath the wood. Nail planks in place.

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