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Build A Koi Pond

Before deciding if you want to keep Koi you should ask yourself this question: "Are you willing to take the responsibility for providing a healthy environment for Koi and doing all that this entails?"

Pond Picture

When building a Pond there are several things you must do in order to keep your Fish healthy, if just building a Water Garden then the following requirements don't have to be met. If you are planning on having Koi, first ask your self "Am I prepared for the commitment of providing responsible care for my fish?" If not, then please just stick to a Water Garden.

Here is a small list of items you need to be prepared for if you plan on keeping Koi:

  • Fish require a commitment of time, money and effort.
  • They need proper nutrition.
  • A filtration unit.
  • They will also periodically require medicines for diseases or injuries. Ideally, you should plan to purchase and learn to use a microscope, primarily for parasite identification.
  • There will be expenses involved for basic water test kits and water additives such as dechlorinator and ammonia binder.

The Charm of a Koi often develops in to a compulsion, but enthusism for collecting and showing these beautiful fish must be coupled with a clear understanding of how you can provide the ideal environment for them. Koi ponds need to be designed and constructed with a focus on Health and Safety.

The Pre-Planning phase is the most important step, make sure and take your time when planning your pond designs. You will save time and money when you pre-plan your pond designs. The worst thing you can do is build on a whim.

The first thing to do is plan your budget. Make sure you know what you need and what it will cost. The larger the pond the larger the expense will be. That means the size of your budget will determine the size of your pond.

If you skip purchasing essential items a koi pond filter, UV ultraviolet light, and a pump) it will leave you with a bad outcome and you will walk away aggravated with the experience.

If you do not feel up to the job you can always leave it to the experts.

The easiest way to build a Koi pond is to create a working ecosystem within the fish pond. The way to create this ecosystem is to combine the following elements. Leaving any of these features out, will cause more difficulties in establishing a balanced ecosystem not to mention more time and money spent on maintenance.

  • Purification system: A Biological filter or Pond filter In a closed water feature (i.e. non-spring fed) you need both a mechanical filter to handle larger debris and a biological filter to remove excess nutrients which cause green, murky water.
  • Pond Pumps: Recirculation of a closed water feature is essential to add oxygen to the water for fish and bacteria. In addition, recirculating water keeps it fresh and allows gases to escape. A waterfall is an excellent way to add oxygen to your Fish Pond.
  • Liners and Underlayment: To greatly reduce water loss to the soil, an impermeable membrane (liner) is mandatory for small water features (under 1000 sq. ft.). A 45 Mil EPDM Rubber Pond Liner is recommended. To pad the liner, an underlayment is recommended. Woven underlayment will allows gases to escape and unlike sand, an underlayment will pad the vertical edges of the liner.
  • Plants, Fish and Bacteria: Plants remove nutrients from the water for their own nourishment. Fish eat insects and in turn fertilize the plants. Bacteria eat the nutrients that create green, murky water therefore keeping the pond clear. Note: Eliminating any one of these variables in attempt to cut corners will increase maintenance and decrease water clarity. By establishing a working ecosystem you work with nature instead of against it.

The reason why ponds do not turn out right is that most people do not do enough research and have insufficient equipment.

When designing your pond it needs to be arranged where the contaminates move from the water into the filtration system. Bottom drains, skimmers and flow patterns will help you move the contaminates toward and into the water outlets.

pictures of water gardens

IMPORTANT: After your pond is built most people make the mistake of adding their Koi or Pond Fish right away. This is the fastest way to kill your Fish. Don't let this happen to you Click Here for Information on Stocking your pond the right way.

Up to 85% of the ponds being built today are so poorly designed that within 2 years, many of the customers are so unhappy with it that they question why they built it in the first place.

Tips on building a Koi Pond that you will enjoy.

  • If it is built without a bottom return drain there is no way for the fish waste to get from the bottom into the filter where it can be removed.

  • If you fail to install a skimmer you will be required to constantly net leaves off the surface.

    If rocks are placed on the bottom to hide the liner they will create pockets for fish waste and leaves to collect. As these leaves decay they will give off a toxic acid which will cause the water to turn to a "root beer" color. The only way to solve the problem is to remove the fish, completely drain it and then pressure wash the whole pond bottom.

  • Poor Shape and Contour.

    Many ponds are built too small to properly support Koi, they need at least 1500 gallons.

    A pond should be at least 4 feet deep with no area less than 3 feet deep. Ponds with shallow areas near the edge will allow predators to dine on your fish. Even shelves for plants can create a potential problem with predators.

    A pond with a flat bottom, even if it has a bottom drain return, will be hard to keep clean.

  • Poor Filtration.

    Unwisely, this is where people often times try to conserve money. A filter that is not properly designed or to small will never provide clean, healthy water. Many filters are also, extremely hard to maintain, requiring regular washing of mats, brushes and sponges and are full of fish waste.

The trick of low-maintenance construction is to think external. Use an external filter to keep your pond clean and healthy, an external pump to keep it flowing and an external UV Light to keep it clear. Just the fact that you have located the equipment where you can easily get to it is half the battle. When you build a pond make sure you have a bottom drain, this will make your job alot easier. The #1 Most Effective Piece of Equipment to Make the Pond Low-Maintenance is a Bead Filter or a Bog Filter.

A couple of points to remember:

DO NOT Line the Bottom with Rocks!

The Bigger the Pond - the Easier to Maintain!

To keep your water clear install a UV Light.

Here are some water features that you will need when you building, and what functions they perform.

The first requirement is that it must contain moving water.

A pump is used to draw in water and send it through a tube before returning it to the pond above the surface. As it leaves the pipe, it will absorb oxygen before it enters the water.


You will need to allow for an overflow on occasions of heavy rain which suddenly overload the water. Pipes can be placed around the pond just above the water surface, or they can be placed upright. In either case they will exit into the drainage system. Be sure they are covered with a suitable wireweld mesh so the smaller fish will not be carried away. The system described will circulate the water and oxygenate it but it will not remove debris, so this is the need for the bottom drain.

Bottom Drain

When using an external pump you must have a way to pull the water out of the pond. There are several drain methods available: bottom drains that install through the liner, vacuum bottom drains that sit on top of the liner and strainer baskets that cover the end of a hose to prevent fish from being sucked into it.

The most low-maintenance method is installing a 3" bottom drain through the liner. Both the vacuum bottom drain and the strainer caps are unable do as good of a job as one installed into the floor of the pond.

Even a 2" bottom drain with the anti-vortex cover is not as good as the black-domed 3" bottom drain because it traps leaves and large debris at the cover and does not allow it to go out of the pond and into the leaf basket of the external pump. That trapped debris has to be pulled off periodically with a net or pole of some kind so there is a little more work to it. Although the 3" dome allows leaves and large debris to leave the pond it also sucks in small fish so one has to accept that he will need to rake off the top of the 2" periodically if the fish are less than 6" long.

The drain cover is best made from an inert material such as PVC so it will not rust or release chemicals in so doing.

Where the bottom drain is located can mean the difference between a "self-cleaning" pond and one that needs attention. It should be placed at the deepest part and the floor of the pond should slant gradually down to the drain to encourage all the debris to fall toward the drain. It should be installed half-an-inch lower than the ponds floor and be located as far away from the water return as possible to encourage healthy water circulation.


A depth of at least 4 feet (1.2m) is recommended for large Koi. Avoid ponds less than 4 feet (1.2m) deep because of the potentially of severe fluctuations in water temperature. Koi swim both vertically and horizontally, so depth gives them space to exercise, freedom of movement, and the opportunity to live a more comfortable and stress-free life.

You will also need a depth of 4 feet so your fish can survive through the witner.

Know Your Frost Line! This is the deepest your water is likely to freeze in the winter with extended periods of low temperatures. Your pond needs to be at least 6" deeper thean the frost line to be able to overwinter your fish.

Pond Picture

Liners Or Preformed Shells

  • Liners allow you to be more creative with the shape of your pond. You must conform to the manufacturer’s idea of the perfect pond if you use a preformed shell.
  • Preformed Shells are not deep enough - a must if you want to offer your fish protection from predators and to overwinter your Koi.
  • It saves you no time to put a preformed shell into the ground. In fact, it costs you another step to backfill to fit the shape of the shell.
  • You can not put maintenance-saving bottom drains in the hard plastic shells.
  • When the ground shifts (as it often does) the form will shift with it and your carefully constructed leveling job will be for naught.
  • Forget putting that beautiful large boulder on the lip of the preformed shell. It will crack under the weight.

Click Here for the Winter Pond Article.

Budget and Supplies

When planning your budget, do allow for the buying of your Koi fish themselves and for such things as plastic containers to inspect them in, driving nets, and certainly a spare tank for isolating a sick fish. These can be made out of the least expensive pond liners, or you could even use a child’s inflatable pool. You will need various water testing kits so you can be sure of the water quality. For more on the Quarantine Tank Click Here.


If you want to make a natural looking waterfall, you can use the same stone that was used around the pond. Place flat pieces of stone onto a bed of mortar, on steps you formed in the compacted mound of soil. Make the waterfall’s path as irregular as possible.

At the top of the waterfall, incorporate a waterfall box or a hose feeding from the pump via the pond’s filter. You can now trim any excess garden liner. Once the waterfall is set and is running with water, position additional rocks to fine-tune the flow of water down the waterfall.

Conversion Tables Click Here
Nishikigoi Terms Click Here

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koi fish pictures

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Container Water Garden

One of the easiest ways to try your hand at water gardening is to create a miniature pond in a Container Water Garden. Choose a container at least 18 inches in diameter-24inches is better.

Are You A School Teahcer and Need A Fun and Educating Project for Your Kids To Do This School Year?

How about Build your Own Koi Pond? On this Pond Activity Guide it has the steps for building a Pond for all Grade Levels.

Pond Activity Guide

Building For Koi

Since Koi can become very large fish as adults, a pond designed as a habitat for Koi must include the necessary volume, configuration and filtration for that purpose. A minimum pond size requirement should be met as determined by the gallons of water per inch of fish ratio. A good stocking guideline is no more then one Koi per 200 gallons. This means a Koi pond is designed differently than a pond intended for smaller fish or just plants.

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How to Glue PVC Pipe

  1. Square pipe ends and remove all burrs, dirt and debris.
  2. Check the dry fit of the pipe and fitting. The pipe should easily fit in one-third of the way. Pipe should not bottom when dry; it should be a snug fit.
  3. Clean pipe and fitting with PVC cleaner, then prime with Purple Primer. Choose proper PVC cement based on desired cure time (regular cement requires 24-hour cure vs "Rain Tight" 1-hour cure for low-pressure applications).
  4. Apply a thin coat of PVC cement to fitting, avoiding puddling inside of pipe. Make certain the entire socket surface is covered.
  5. Apply a liberal coat of PVC cement to pipe. Make certain the entire pipe surface to the socket depth is covered.
  6. Quickly assemble parts. Cement must be fluid when attaching segments. If not, reapply cement to both parts.
  7. Push pipe FULLY into fitting using a 1/4 turn motion until pipe bottoms.
  8. Hold pipe and fitting together for 30 seconds, then wipe off excess glue with a cloth. Watch that it doesn't creep back.
  9. Keep cement container tightly closed when not in use.
  10. Do not pressure test until cement is fully cured, usually 24 hours.

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