Last update: August 4, 2022

DIY Koi Fish Pond: What Do I Need To Build a Backyard Pond?

If you’ve been considering adding a Koi pond in your backyard, then you would be making the right choice.

Lots of people are not sure of the benefits of Koi ponds but rest assured, there are many.

Lots of people believe that they bring strength and good luck. This is why the Japanese culture cherishes Koi fish and its relation to good fortune and luck. It’s also a natural beauty that brings an instant facelift to your backyard or outdoor living area.

Koi fish have also been known to bring serenity and reduce stress, and they are one of the lowest maintenance pets to own. So let’s take a look at how you can build your own Koi pond with water in your backyard.

How to Build a Koi Pond?

lady sitting by the koi fish pond

There are lots of variations when it comes to backyard ponds, and depending on the type you choose, you’ll require different types of equipment.

Some of the factors to take into consideration before or while planning your Koi fish pond include:


You need to take into consideration whether there are trees in the area. If there are, then you need to steer clear of this space. Also, keep away from areas containing electrical lines. It there is rocky soil, you may need to use an underlayment material to prevent holes in your liner.

Sun exposure

In the event of getting full sun on the pond the entire day, then you need to have sufficient filtration. This includes both mechanical and biological to prevent heavy algae buildup and keep the water clean.

Size of the pond

While it may seem some easier to build and maintain a smaller pond, the reality is that a larger pond makes it’s much easier to keep your pond balanced and also allows you to hold Koi and pond fish. However, putting in a larger pond means larger equipment that is required such as filtration, liners, and pumps.

Quality of the pond

If you want as little maintenance as possible when it comes to your pond, then a filter will be needed to keep it clean with very little effort from your end.

So once you figure out all of the nitty-gritty details and exactly how you’d like to customize your backyard pond, you can go ahead and get into the planning phase.

Building a Koi Pond – Step by Step

Step 1

When creating a pond, steer clear of trees especially those that have deep roots and any area containing electrical lines. Instead, choose an area with either partial or full sun if you’re planning to keep fish safe and plants.

Step 2

koi pond outline with the help of paint

Using marking paint, you need to outline the outer pond areas and exactly where you are going to put the pump, filters, falls, etc. Start by digging tiers and shelves, which will initiate the excavation process. A point to note is that the bottom tier should be at least 4 feet deeper pond to accommodate hardy fish during wintertime.

Step 3

Backfill and place both the spillway and skimmer. In this step, you also need to roll out the placement of the pressurized filter and flex pipe.

Step 4

adjusting liner for building a koi pond

You need to use underlayment and lay it down on the entire pond and fall area and thereafter, use a 45 mil EPDM liner. The liner should extend beyond the limits of the pond by at least 1 ft to allow for rockery over winter and settling earth. To prevent the liner from escaping from its position, extend it behind the waterfall as well.

Step 5

In this step, you need to attach the liner using a lap sealant to the skimmer. The bolts and nuts will also be provided with a skimmer. Thereafter attach the liner to the upflow spillway, or alternatively, you may have the liner coming behind the spillway if there is no faceplate.

Step 6

In step 6, you need to start by placing your stone or rockery. Begin with the larger rocks and work your way down to the smaller ones. The stones should be worked into the first shelf of the pond and also on the top surface so that it can hold the liner securely in place.

Step 7

Use waterfall foam in the stream as well as close to the spillway, and between the rocks to prevent water from disappearing through the stones as it travels.

Step 8

In this step connect the skimmer pump to the spillway using PVC flex pipe and situate the pipe in the back skimmer. Connect the solids handling pump to the pressure filter and from the pressure filter back to the spillways or directly into the pond.

Step 9

Fill the pond water. Add dechlorinated water and also add some beneficial bacteria. Switch on the pumps and the filtration and to ensure that all is running smoothly.

Step 10

finishing touches while building a koi pond

Now that all of the legwork has been taken out of the project, you can start to add the finishing touches. Plant around the pond to create a more natural setting. Plants and fish can be added after a few days once the water temperatures have warmed up. Along with the fish, you should add aeration. This is optional, but lighting can also be added at any time either inside or outside the pond.

What Equipment Do I Need to Keep My Fish Alive in the Pond?

You’ll need the following equipment to build a Koi Pond for your Koi Fish.

Pond filter

When it comes to pond filtration systems, there two types. The first is an ultraviolet clarifying filter, which basically kills green water and keeps the water clear. The second is a biological filter that looks after the quality of the water and keeps the fish happy and healthy. And as a bonus, it provides ease of installation.

So is a mechanical filter necessary for building a pond? The simple answer is no. If you’re not planning on keeping any fish or are simply planning to keep a few fish and plants, then you don’t necessarily need a filter. You can create a natural balance instead.

Alternatively, if you’re building a Koi pond, and you definitely want a filtration system to take the legwork out of maintaining it, then you have two options. You can either choose the biological filter or the UV clarifying filter.

Pond skimmer

Irrespective of whether you are creating a pond or not, a skimmer is a method of filtration. Ultimately, filtration is a method of removal. When using a high-quality skimmer, it will improve the condition of your pond. The skimmer basically removes all types of impurities from the pond.

These impurities can be anything such as pollen, grass clippings, leaves, seeds, and floating algae. While all of these materials are 100% natural, in the context of pond water quality, eventually they leave the pond with a foul smell and an unhealthy habitat for the fish. So if you are planning on building a Koi pond, then a skimmer is absolutely essential to keep your pond muck-free.

Skimmer Net

skimmer net for cleaning the koi pond

A skimmer net is basically a useful tool that helps remove algae and other types of larger debris that are floating in the water from the pond. It’s also useful in removing uneaten fish food and dead leaves as well that fall into the pond. It is especially useful to remove ornamental fish from the pond when you are cleaning the pond or inspecting a sick fish.

UV Steriliser

A UV sterilizer is an amazing device you use to keep your fish aquariums clean. It is used in fish tanks and aquariums to get rid of algae, bacteria, and other parasites like Ich. Ultimately, it acts as a prophylactic and is a safety device for your fish tank.

They can be used both in fish tanks and other types of aquariums. Ultimately, it’s an asset to your tank due to the protective nature. You’ll also be able to enjoy your tank even more since it makes the water crystal clear. UV sterilizers are widely used, although the purpose is still widely debated.


While you don’t necessarily need to have an aerated pond, a properly designed and installed aeration system will significantly slow down the eutrophication process. Thereby this helps prevent winter and summer fish kills and also prolongs the life of your pond.

However, the key phrase here is that it needs to be “properly designed and installed.” If you’re looking at building a fishpond or building a large one, then an adequately aerated pond will hold twice the amount of fish than anon-aerated one.


A pond thermometer will provide you with one of the most valuable pieces of information when it boils down to taking care of your fish, and that’s water temperature. Water temperature lets you know when and what types of foods you should be feeding your fish.

One of the only ways to deduce water temperature accurately and feed your fish accordingly is to know the temperature of the water inside the pond. If you don’t have a thermometer at the moment, it’s about time you get one, instead of playing the guessing game with the health of your fish. If the temperature of the water is lower than 70°F,  it lets you know that you start mixing your fish’s diet with a wheat germ that is low in protein.

When the temperatures drop below 60° F, the diet should be switched to wheat germ exclusively. Proteins are harder to digest by your fish than other nutrients. Wheat germ will continue to feed your fish if the water temperature doesn’t get below 50°F. Once the temperature drops below 50°F, it’s time to stop feeding them until spring.

Water test kits

Pond water test kits are an ideal way to get an idea of any imbalance that could be causing problems with your pond ecosystem. Your fish have become sick or discolored, or if there is an unpleasant odor in the water, these are all possible indicators of an imbalance resulting from something in the water.

This is exactly what a water test kit will help you ascertain. They may not be able to solve the problem by themselves; however, they can accurately pin-point it for you and therefore set you in the right direction to find an adequate solution.

Testing the pond water and learning all about what makes a pong habitat thrive is a great way for budding aquarists to begin to learn more about what contributes to a healthy pond environment.

Winterizing your Pond

waterfalls in pond with koi fish

If you’ve never winterized your pond before, it may sound like a tedious process. Of course, you need to say goodbye to your colorful little friends for a few months, but a few simple tips to ensure that your fish are ready to greet you once spring arrives. So here are a few things to do to winterize your pond.

Remove Debris and Leaves

Placing a pond net cover over your water feature before you the leaves and debris start falling is one of the easiest ways to keep your pond well maintained and hassle-free.  This is one of the easiest and most ideal ways to manage and gain control of your pond.

Once all the leaves have fallen, simply roll up the net and put it away until you need it again. If you didn’t install netting when you built your pond, you’d likely have a build-up of the leaves that need removing.

In order to remove the leaves, use a long handle pond net to make light work out of this task. If you’re feeling a bit too lazy to work on the mess, then you will have quite a job waiting for you when spring arrives.

Trim Dying and Dead Foliage

By trimming dead foliage, it helps remove excess leaves that would otherwise decompose in the water. So cut back on unwanted foliage around the edge of the pond that would otherwise droop into the water.

Add Cold Water Bacteria

Coldwater bacteria, such as Aquascape cold water beneficial bacteria, will keep your pond water clean and clear. This bacteria contains concentrated strains of beneficial bacteria developed to work in temperatures that go below 50°F.

Regular use of this type of bacteria will help maintain the quality of the water as well as the clarity of the water. It will also dramatically reduce spring maintenance by digesting debris that may accumulate throughout the winter months.

Pond Netting

Pond netting is priceless during the winter months. It is laid over your Koi fish pond and catches any falling debris and dead leaves. In fact, it will hold any type of dirt and keep it from falling into the pond water, preventing a bigger mess for you in the spring-time.

Pond Heater

Pond fish tend to have a hard time during cold winters. While koi pond filters function adequately in the summertime, they tend to have difficulty in winter owing to ice formation. As a result of this, the water will continue to lose oxygen and will also become dirtier.

The solution is to warm up the pond water. This can be achieved by using a pond heater in the winter months. There will be less ice formation, and the water will absorb more oxygen level, and harmful gases will be removed.

Introducing and Acclimating the Fish to the Koi Pond

koi in pond

If you are new to being an aquarist or fish owner, then you need to understand that fish must be acclimatized when bringing them home from the store. To acclimate your fish simply means to equalize the water temperature between the bag you bought them in at the pet shop and the new outdoor pond oasis, aquarium, or fish tank in your home.

So you will need to equalize the pH levels, and equalize the water parameters, and this will ease the transition from one aquatic environment to another for your pet fish. So one of the best ways to go about acclimating your fish is to float the bag on your fish tank. The bag should float for approximately 15 minutes to equalize the temperature.

You can also use a cup and scoop up some of the aquarium water, and place it inside the bag. You should open the bag and pull down the plastic to create air bubbles around the bag, which will allow it to float on top of the fish tank or fishing aquarium. If it’s not stable enough, then roll down the top of the plastic a few more times until the bag feels more stable floating on top of the water.

Float the bag for anywhere between 45 minutes to an hour and then scoop out the fish using a net and add them to the pond. Any water inside the bag should be thrown away and not poured into the fish tank. It could have stray parasites or strands of bacteria, and you don’t want that getting to your fish’s aquatic environment.


If you would like to bring some of the exotic beauty from the Far East into your everyday life, a beautiful Koi pond is the answer. These ponds are designed to be peaceful and relaxing and bring positive energy to your home.

Owners of backyard Koi ponds say that they are less stressed, more relaxed, and have a more positive outlook on life. Koi ponds can also help give your outdoor living area a much-needed facelift due to its natural beauty.

It is believed, in the Japanese culture, that Koi ponds bring strength and good luck to the home it is situated in. It is also one of the lowest maintenance pets to own. They stay outside all year round and don’t require much work, unlike having a cat or dog.

Having a Koi pond will also help increase your property value. An attractive and exotic looking pond appeals to prospective buyers, and the unique beauty of the finished pond will make buyers feel like they should be paying a higher price.

Ian Sterling

I've been keeping fish for over 30 years and currently have 4 different aquariums – it's an addiction. I'm here to teach you everything there is to know about fishkeeping.

I also use this site as an excuse to spend lots of money on testing and reviewing different aquarium products! You can find my reviews here.

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