Building a Koi Fish Pond – Posted in: PONDS

There are millions of koi fish collectors around the world and the numbers are growing each passing day.An important aspect of koi fish collection is a koi fish pond. This is where you will keep your koi and for serious enthusiasts, your pond will be home to new koi fish that you bred yourself. There are various ways to build a koi fish pond using different types of materials. You can build them in the ground or on the ground, you can even combine both.

No pond will look alike but they should all be built with basic fundamentals. Here are some foundational parts of a koi fish pond that owners should have:

  • Biological filter
  • Pond Skimmer
  • Pump
  • Bottom Drain
  • Aeration system
  • UV clarifying system
  • Minimum depth of 3 feet

Koi ponds are different from a water garden because the fish determines the type of plant life that can be grown. Koi fish eat some plants, they also grow in size which makes the size and depth of your pond bigger than usual. Water gardens may have goldfish and aquatic plants and their depth can be at least 2 feet deep.

Thing to Consider When Building a Koi Pond

building a koi pond

Pond Location

The first step in creating your koi fish pond is choosing the best location for your pond. This is one of the biggest challenges new pond owners face.  A koi pond that is hidden or hard to access defeats the purpose of why you are building a pond in the first place. Having to go through a maze of obstacles before reaching the pond just to see your koi isn’t appealing to guests or clients who may want to view your fish.

You need to take note that koi ponds would be easier to maintain if they are in a shaded area rather than outside under full sunlight. Choose an area where you can see the pond all year round. The view should be unobstructed. Ponds can attract wildlife like birds and butterflies so they can be quite a sight to behold. You have a living ecosystem right in front of you. Your koi pond should blend perfectly with the surroundings, it should appear as a natural part of the landscape. 

Too much sun will cause more algae to grow and it can raise the temperature of your pond and may become too hot during the summer season.It would be great if you can see your pond both from inside and outside your home. Once you are satisfied with your pond location you can now start digging. Stay away from trees with huge roots and avoid electrical lines. You can use a Pond Calculator for planning the next step.

Pond Size

large koi pond

The next step is knowing how big your pond will be. You should trace it out on the ground. A common mistake made by first-time pond owners is building a pond that is too small. Outline the pond perimeter and trace where other components will be placed like the skimmer, falls, and filters. Mark their locations with marking paint. If you are building a pond for koi fish, the minimum size requirement is 1500 gallons. This may sound huge for newbies but experienced collectors know that a pond with a smaller capacity will not make you happy in the long run.

A larger pond makes it easier to keep water levels balanced and also gives you the chance to keep more koi fish. This means having larger pumps, filters, and liners which will cost more. You can now start digging your hole, the ideal depth is 4 feet minimum so that you can hold your fish over the winter.

Tank, Waterfalls, and Equipment

Position the skimmer and spillway then backfill. Prepare the placement of the flex pipe and the filter which is usually placed behind the falls. Pond skimmers should be buried at a certain level beside the pond. A ditch should be provided for the plumbing from the pond to the waterfall up to the pond filter. The filter serves as the heart of your koi pond. It keeps the water clean and healthy for your koi. Don’t make the same mistakes of owners who chose to spend more on making their pond look good rather than investing in a good filter.

Filters have two purposes, they remove fish waste and any debris from the pond and it also converts the ammonia produced by the fish into nitrates which are harmless to the fish. A mechanical filter and biological filter is needed to fulfill both functions. To keep your koi fish healthy you need to add a bacteria tank so that your pond water will be fit for koi to live in. A common design for bacteria tanks is using them like a waterfall into the pond. A pond needs water circulation for koi to thrive. 

Parasites in your water can be silent killers. You can’t see them which makes them more dangerous than the common bird and animal predators. Fish parasites can cause disease and could turn into fish kills if not dealt with properly. Installing biological filters in the waterways of your koi pond is a surefire way of preventing an outbreak of parasites in your pond.

The sound of running water adds to the serenity that a pond gives to its owners. This is why adding fountains and waterfalls are popular among koi fish pond collectors. Bottom drains are a standard with a four-inch pipe leading out is ideal. Organic matter, leaves, dirt, and debris will all collect at the bottom of your pond. Once they build up they can make your pond stink. A bottom drain sucks all of this up and sends it to the filtration system for disposal. A 6000-gallon pond can work properly with a single bottom drain.

Pond Underlay

Thick filter cloth material is commonly used as an underliner for your pond. Use scissors or a utility knife to cut them. Tape small pieces together to keep them from getting out of place as you position your pond liner. Proceed with lining the whole pond and falls area with underlayment and EPDM liner. Make sure that liner extends up to a foot beyond the perimeter to give space for settling dirt and rocks over the winter. The same is done behind your waterfall to stop water from leaking. Anchor with large rocks and smooth out the liner. Avoid ripping your liner when you are roaming around your pond. Folds and wrinkles in some parts can’t be avoided but some will be necessary. Folds will flatten when the water is added to your pond.

Adhere Liner

Owners want to enjoy their pond longer compared to performing maintenance tasks.  Why not invest in filters that have a backwash system that makes cleaning them quick and easy. A skimmer with a skimmer pump can draw surface water into a net to keep your surface free from leaves and other debris. Connect your liner to the skimmer using a lap sealant. Nuts and bolts are included in the skimmer. Attach the liner to the upflow spillway.

Adding Rocks

Place your stones starting with the bigger pieces first and work down to the smaller ones. Edge stones should be used to hold the liner in place. Rocks should be safe for your koi, avoid ones with sharp edges as they may kill your fish. Smoother rocks on the sides and bottoms are ideal for koi ponds. Use waterfall foam in-stream close to the spillway and between the rocks to avoid water from being out of sight.

Plumbing Connections

Connect your skimmer pump to spillway using a PVC Flex pipe and install your pump behind the skimmer. PVC Flex pipes are durable and flexible and are used with PVC fittings that can withstand sunlight and freezing temperatures. Use PVC glue and primer to fuse the fittings to the pipe. Choose a circulating pump that has enough power for the size of your koi pond. Make sure the pump is an inch or two off the bottom of the pond floor to keep it from sucking up sediments. Pumps have different sizes and power. Choose ones that are energy efficient because they have to be working the majority of the time.  Fill the pond with water and make sure pumps and filters are working smoothly. Add your de-chlorinator. As preparation for koi fish. Make sure that your pond retains water before adding plants and fish. 

Finishing Touches

You can add aquatic plants to have a more natural look. Most of these plants are good at using up the nutrients in the water to prevent the growth of algae. Water Hyacinth, Bacopa, Anacharis and Parrot’s feather are good to add to your pond. Water lilies can give added shade to your pond and serve as a hiding place for your koi when predators abound. Add your koi a few days after or until water temperatures have become warmer. Make sure that there are no leaks in your pond and water is properly circulating.

Aeration should be added once koi is introduced into the pond. Pond aerators produce more oxygen for your pond. It is normal for oxygen levels to drop in hot weather and during night time. This is why supplemental pumps are used to oxygenate your pond water. Lighting can be installed in or outside the pond. This makes your pond visible at night when most of your family are at home. 

Protect your Koi from Predators

Koi fish are tasty for predators like cats, raccoons, and blue herons. You need to guard against these known enemies of your koi unless you want to end up with a pond without any koi fish in it.

Floating Mesh

One of the best ways of protecting your koi fish from predators is by installing a floating mesh on your koi pond. We recommend a UV resistant floating mesh that you can buy from your favorite hobby shops. They appear invisible from afar and don’t cost that much. You can sleep well at night knowing that birds and land animals can’t reach your koi as you enter into dreamland at night.

Hi Tech Gadgets

For those who love high tech equipment and gadgets there are ultrasonic gadgets that makes noise whenever a bird or animal approaches your koi pond. The ultrasonic noise can only be heard by animals and keep them away from your koi. The gadget will not disturb anyone because the sounds produced are not audible to the human ear.

Automatic water squirts can drive away cats and dogs who may want to feast on your koi. Place them around your pond and once their sensors are activated they can squirt water on any animal that is trying to breach the pond perimeter.

Fish Cages

Your koi fish can have their own houses beneath the pond surface. These koi houses are made from mesh cages and they can be the perfect hiding place for your koi once they detect danger. Make sure to pick a fish cage with a large entry that koi fish can easily swim into for hiding.  This trick may not work well with swift flying predators so the floating mesh is still your best option.

Natural Barriers

You can also come up with natural barriers to protect your koi from predators. Plants, vegetation, statues and rocks can keep land animals from coming into contact with your koi. Aquatic plants can shield your koi from predatory birds.

Building a Pond Takeaways

There is no one size fits all in building a koi pond. You can achieve success by choosing any method in building a healthy pond. Some owners don’t believe in bottom drains and some won’t use liners. At the end of the day, it will all boil down to finances and preferences. More than the foundation of your pond, the components that you should invest your energy and finances on is your pump and filtration system. They serve as the heart of your pond system and will keep your pond and koi thriving.