Koi Carp: The Definitive Guide To A DIY Pond


Lazlo Ilyes

Every garden needs water to make it complete. It is an integral part of nature and the lifeblood of the planet. Japanese gardeners recognised centuries ago that water and the fish that inhabit it brought a sense of calm to their land. Water is a vital component of all zen gardens.

Koi carp is the ideal choice of fish thanks to their bright colours and gentle movement. The crystal clear waters suit a contemporary setting well, where every part of the garden is micro-managed, and there is not a leaf out of place.

If you would like to keep Koi but are unsure about how to go about it, here is how to go about building the perfect pond in which they can live.

The Foundation

This pond will be raised from the ground so we will need to provide adequate foundations for the walls. It is not a complicated job, but it involves some heavy work.

  1. Mark out the line of the walls on the ground according to your measurements
  2. Dig a trench and make it thirty centimetres wide by thirty centimetres deep.
  3. Ram the bottom of the trench to make it firm.
  4. Fill it halfway with a layer of sand and hardcore. It is available in bags or by the ton from your local DIY store.
  5. Ram or use a vibrator to compact it until it is solid.
  6. Pour the concrete in the trench up to ground level. Mix it with one part, two parts sand, and two parts gravel. It is best to use a mixer unless you have much stamina; it is backbreaking work.

The Walls

Construct the walls from brick, block, or stone. Lay them with a mortar mix of one part cement to five parts building sand. Use a spirit level to make sure the walls are vertical. Lay as many courses as you need until they are complete. When the liner is in place, fit the capping stones to finish the walls and hide the edges of it.

The Liner

Fit the liner in next. It will take some time to get it into the right shape. Persevere until you are happy with it. Fill the pond with water to push it into its final form. When the liner is in place, trim it so that it overlaps the top of the wall by about two inches.

Water Quality

Contrary to popular belief, the water in a Koi pond doesn’t have to be clear, but you can see the fish better than if it is brackish. You need to keep the water healthy. Fish need to breathe, and this great pond aerator is perfect for adding oxygen to the water.

The filter will have three main parts.

  • The mesh will stop any large objects from getting in.
  • A sponge will filter out medium particles.
  • Bacteria grow in a suitable medium and will remove toxins such as nitrites from the water.

You can also use a UV filter to help keep the water clear. It kills algae as the water passes through a tube surrounded in intense UV light. Ordinary filtration is not always enough to clear the water.

Build your own pond and start collecting Koi today. It is an addictive hobby and an enjoyable one.

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