How to Build a Koi Pond

How to Build a Koi Pond

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how to build a koi pond

This HBV Series Koi Pond at Russell Watergardens & Koi’s Flagship Store in Redmond, Washington is as beautiful as it is functional. It was designed to allow maximum interaction between the lovable Koi and the people who love them.


The Koi pond itself is 6′ wide by 12′ long and 4′ 6″ deep with 1½’ above ground and 3′ below ground.

We didn’t make it deeper because of a sewer line running directly underneath the pond – and we didn’t want to raise the sides above children’s viewing levels.


This Koi Pond was built using a custom HBV-21 Series Koi Pond Kit.

This koi pond is 3′ below ground and 1½’ above ground. The pond’s walls are constructed with treated 2″x6″ boards screwed to treated 4″x4″ posts. The outer facing of the pond was then detailed with decorative Cultured Stone, the flower bed around the pond skimmer is created with retaining wall blocks. A total of 6 4″x4″x8′ posts and 30 2″x6″x12′ boards are used in this construction.

This Koi Pond features a HydroBead Vortex™ HBV-21 filter, Hydro Centrimax™ HC-58-45 centrifugal pump, Piper HydroClean™ Pond Skimmer with Bottom Drain Inlet, HydroUV™, HydroAir™ HA-1500 air pump, Bottom Drain with HydroSieve™ Bottom Drain Pre-Filter, and an Aeration Tower™ to minimize the visual surface tension disturbance caused by bubbles in the pond. The result is a clear, undisturbed vision of the Koi at all times – without having to turn OFF the aerator! (Aeration Towers™ are another Russell Watergardens & Koi invention)


Building a Koi Pond is easy – simply follow these procedures outlined in the following series of photos.

Start out by creating a rough drawing of the pond and where you want the filtration system to be located.

In this case, the pond is a 12′ long by 6′ wide rectangle. The Piper HydroClean™ Pond Skimmer is installed 18″ back from the pond’s edge, and both the HBV-21 filter and HC-58-45 centrifugal pump are located about 18′ away from the pond.


Next, paint your drawing on the ground in “actual size”.

!!! Make sure to always call your local Utilities to locate underground pipes and wiring before you dig !!!

Digging with a small excavator from your local rental place makes for a much easier time.


A small excavator easily digs the hole for the pond, and loads wheelbarrows for easy soil re-locating.

In this case, much of the excavated soil will be re-used to hide the HydroClean™ Pond Skimmer and to create a raised flower bed at one end of the pond.


Use the excavator to do the “heavy” digging. Then, fine tune the excavation by hand with shovels. The excavation should be at least 1 foot longer in every direction to allow construction of the retaining walls.

In this case, the finished pond will be 6′ x 12′ so the excavation is 8′ x 14′.


A Koi Pond retains the earth “behind” the liner. Many different types of materials can be used to retain earth – from treated wood, to concrete, to concrete blocks. In this case, we are using pressure treated “ground contact” lumber for its ease of construction and relatively low installation cost. The design is simple, 4″ x 4″ x 8′ posts on all four corners and one additional post in the middle of each 12′ side for a total of six posts.

Dig each post hole 18″ down by 12″ wide from the bottom of the pond excavation. Set the 4″ x 4″ posts in the holes and fill with concrete – just like setting fence posts.


Using Stainless Steel deck screws, attach the pressure treated 2″x6″ retaining wall boards to the posts to hold them level while the concrete in the post holes dries.

Construction of this Koi Pond was during business hours at our Flagship Store in Redmond, WA – thus the use of traffic cones to warn customers of the construction area.


This photo shows why the excavation is one foot larger in all directions than the finished pond. It gives you room to work down in the excavation. Once all the retaining wall work is completed, you can backfill the extra excavation space with soil previously removed.

The 2″x6″ boards hold the posts level while the concrete at the base dries.


Place a layer of soil over the concrete in the post holes to prevent any sharp or abrasive edges from causing harm to the pond liner.


Its a good idea to let the concrete holding the posts cure overnight to ensure they won’t move out of level when you start attaching the retaining wall boards.


Once the concrete holding the 4″x4″ posts has cured, you can begin attaching the 2″x6″ boards to the posts. Its a good idea to use Stainless Steel screws – they cost more – but they won’t corrode and fail over time. Attach the 2″x6″x12′ boards to each side, and cut a 2″x6″x12′ in half to make 2″x6″x6′ boards for each end. Each side and end will be 10 boards high.

Again, you can use many things to retain the earth, this example shows how using pressure treated lumber is quick, simple, and cost effective.


In this case, the pond design calls for 3′ below ground, and 1½’ above ground – so you can see, the use of pressure treated lumber makes this easy. You’re simply making a large box.

The limitation of lumber is that curved walls are not possible. For curved wall designs, poly urea, concrete – or gunite can be used.


With the pond box/retaining walls completed, you’re now ready to place the HydroClean™ Pond Skimmer. In a square or rectangular Koi Pond design – place the HydroClean™ Pond Skimmer’s inlet pipe near a corner for maximum surface current draw.


Mark the spot where the HydroClean™ Pond Skimmer’s inlet pipe will draw water from the pond’s surface. Then, using a hole saw, drill a hole through the wood.


You can see the HydroClean™ Pond Skimmer’s hole cut through the wood. Next, you’ll want to use a smaller hole saw to drill a hole for your main water return line. Water exits this Koi Pond in two places – the Bottom Drain at the center of the bottom of the pond and the Pond Skimmer in the upper corner of the pond.


To create a circular water movement flow – install the main water return in the opposite corner of the same end of the pond as the pond skimmer near the middle depth of the pond. This will cause the water current to create a “vortex” that will cause fish waste to drop to the center of the pond where the Bottom Drain is located.


Next, using the hole saw again, drill a hole in the wood for your UV Water Return. It should be in the opposite end and opposite corner from the Main Water Return. This inlet should be near the bottom to increase the current at the bottom of the pond and to “push” debris out of the corners where it will then get drawn into the vortex current and into the Bottom Drain for removal.


Notice the skimmer outlet near the upper left, and the Main Water Return inlet on the right side near the middle depth of the pond.


Install the Bottom Drain pipe under the retaining wall towards the HydroClean™ Skimmer location. The Bottom Drain should be at the lowest point in the pond. Slope the pond’s bottom towards the Bottom Drain at a rate at least 1″ downward per foot of horizontal. The Bottom Drain has three pieces: Drain Housing, Gasket Seal, and Drain Dome.


Glue flexible PVC pipe to the Drain Housing. Run the flexible PVC pipe through a small trench dug into the bottom of the pond under the retaining wall boards, and up to the lower inlet of the HydroClean™ Pond Skimmer. Remove the Gasket Seal and place a plastic bag over the Drain Housing to prevent soil from falling into the drain when backfilling with soil.


Next, slip your HydroClean™ Pond Skimmer Remote Installation Pipe through the hole cut in the pond box/retaining wall.


For this installation, we’re using 4″ PVC pipe to set the Piper HydroClean™ Pond Skimmer 18″ away from the pond’s edge. Apply a solid bead of the Silicone that’s included with the skimmer to the inside edge of both ends of the skimmer’s Remote Installation Coupler.


Slip the Siliconed Remote Installation Coupler onto the HydroClean™ Pond Skimmer’s inlet pipe and onto the Remote Installation pipe then tighten the Stainless Steel clamps at each end to lock it all in place.


Attach the Bottom Drain pipe to the inlet of the HydroSieve™ Bottom Drain pre-filter. Connect the outlet of the HydroSieve™ to one side of a three way valve, and an outlet of the HydroClean™ skimmer to the other side. The centrifugal pump will pull water from the center of the three-way valve. This lets you control how much water flows through bottom drain or skimmer.


Extend the UV Water Return pipe through the hole cut in the pond box/retaining wall. Extend the flexible PVC pipe around the pond box/retaining wall to where the HydroUV™ Clarifier will be installed. Liner will get attached to this pipe the same way liner attaches to HydroClean™ Pond Skimmers – with a rubber collar and Stainless Steel clamp.


In this design, the HydroClean™ Pond Skimmer’s Remote Installation Pipe is 4″ rigid PVC, the Bottom Drain and Main Line pipe are 2″ flexible PVC pipe, and the HydroUV™ pipe is 1″ flexible PVC pipe.


HydroClean™ Pond Skimmers are designed specifically to give you – the pond builder – the most installation options. HydroClean™ Pond Skimmers attach to any type of pond and any type of pond construction material. Having the ability to be remotely installed away from the pond’s edge, HydroClean™ Pond Skimmers make for more beautiful pond edges. Not requiring weir doors to perform properly, HydroClean™ Pond Skimmers are much safer for Koi than skimmer’s that have weir doors – as Koi can swim into and OUT OF each model of HydroClean™ Pond Skimmer.


With the plumbing lines through and under the pond box/retaining walls – cut the 4″x4″ posts level with the uppermost 2″x6″ retaining wall board.


Next, backfill the “work area” outside the pond box/retaining walls. Compact the soil as you backfill to help reduce future settling.


Installing ½” Styrofoam insulation to the inside of the pond box/retaining walls protects the liner from wood splinters, helps insulate the pond for a more stable temperature, and reduces vibrations and that can startle the Koi. Since this pond is partially above ground, the Styrofoam helps stabilize the water temperature, but also reduces the shock effect on the Koi when children kick the side walls.


The insulation easily cuts around the pipe inlets and outlets. Use Stainless Steel screws or tacks to hold the insulation to the pond box/retaining walls.


It is not necessary to insulate the bottom of the pond – just the vertical walls. A layer of underlayment will protect the liner from abrasive items in the soil.


The pond box is complete, the insulation is complete, the pond’s plumbing is complete – now you’re ready for the next step.


Install underlayment on the bottom of the pond. Cut a hole in the underlayment around the Bottom Drain. Remove the plastic bag that you previously installed to prevent soil from falling into the drain during backfilling.


Next, install fish safe 45 mil EPDM rubber liner. Fold the corners inward as if gift wrapping a present in reverse. Leave at least 12″ over the side walls of the pond. You’ll lock it down later with a cap board or stone.

There are many ways to hold water in a Koi Pond – rubber liner, concrete, and poly urea are the most popular. We’re using rubber liner in this case because it is the most cost effective of the three.


Attaching rubber liner to the HydroClean™ Pond Skimmer’s Remote Installation Pipe is quick and easy. Place a bead of Silicone around the pipe’s outer perimeter. Fold the liner over the pipe like a paper towel over a drinking glass. Place the rubber collar over the liner and pipe. Cut a hole in the middle of the pipe ½ the diameter of the pipe. Push the liner and collar back over the pipe until the end of the pipe squeezes through the hole in the liner. You’ll see how the liner makes its own water tight gasket around the pipe. Then tighten the Stainless Steel screw on the Stainless Steel clamp to secure it in place. You’re done! Simple, quick, and easy.

Repeat the process for the Main Water Return Pipe and the UV Water Return Pipe.


Next, attach the Gasket Seal to the Drain Housing of the Bottom Drain. Cut a hole in the liner equal to the size of the drain hole. Apply a solid bead of Silicone on the flange of the Drain Housing below the liner. Place the Gasket Flange over the Siliconed Drain Housing and install the Stainless Steel screws to lock it in place for a water tight seal.


The Drain Housing, Silicone, Gasket Seal, and Stainless Steel screws all work together to ensure a water tight seal.


The final step in installing the Bottom Drain is to attach the Dome Lid. First, fill the lid with sand or pea gravel for ballast weight. Plug the fill hole with the supplied plug. Then, simply snap the weighted Dome Lid into the Gasket Seal. The Dome Lid has 3 “legs”, and the Gasket Seal has 3 “slots” that hold the legs in place. This ensures suction from the pond’s bottom surface and helps prevent Koi from being sucked into the drain.


The liner installation is now complete. Smooth out the large wrinkles – but don’t worry about the small wrinkles. When filled with water, the water pressure will flatten out most of the small wrinkles for you. (Note the HydroCology™ Water Recycling HydroTanks™ in the background)


Next, lock the liner to the pond box/retaining walls with either a cap board or cap stone. In this case, we are using plastic Trex deck boards. Do not use treated wood here – use only materials that are safe for Koi and friendly to the human touch. Again, attach this cap board to the pond box/retaining walls with Stainless Steel screws.


In this case, we are remotely installing the HydroBead Vortex™ HBV-21 filter and Hydro Centrimax™ HC-050 pump 18′ away from the pond behind bushes in the gardens. We need to excavate a trench for the plumbing lines from and to the pond. Again, a small excavator makes this much easier than digging by hand.


The depth of the plumbing lines varies from one part of the country to the next. It can be as little as a few inches deep in southern states and as much as a few feet in northern states. Here in the state of Washington – we are installing the plumbing lines 12″ down. If unsure in your area, check with your City, County, or State for applicable codes.


In this case, we are using 2″ flexible PVC pipe to and from the HydroClean™ Pond Skimmer, Hydro Centrimax™ pump and Hydro Bead Vortex™ filter. Flexible PVC pipe is quick to install than rigid PVC pipe and requires no fittings to make curves.


We will also install ½” “Funny Pipe” in the trench for the Automatic Water Fill Valve inside the HydroClean™ Pond Skimmer.


In this case, a three-way valve controls the flow between the skimmer and the bottom drain. The UV’s and the air pump get installed inside the valve box seen on the left.


HydroBead Vortex™ filters and Hydro Centrimax™ pumps and been designed to blend in the landscape. In this case, we will be installing the filter and pump in a garden area 18′ away from the pond.


Place the HydroBead Vortex™ filter on firm, solid ground – or, as in this case, on concrete blocks. When full of water, the filter becomes extremely heavy – so you must take steps to provide a firm foundation for the filter to sit on.


When installing the HydroBead Vortex™ filter in the garden, make sure to leave access to the Multi-port Valve for routine backwashing.


Remotely installing your Koi Pond’s filtration system makes for a much prettier pond.


With HydroBead Vortex™ filters and Hydro Centrimax™ pumps, you can remotely install the filtration system virtually anywhere.


The HydroUV™ System gets installed in the ground with the union end and electrical cord pointing skyward for easy bulb changing. In this case, two HydroUV’s are plumbed in series. The two units are connected at the bottom outlet ports. Water enters the first unit on the lower left side of this photo. The water then passes downward through the unit, across to the second unit and upward and out the opposite side of the top near the top of the photo. Later, a valve box will be installed over the HydroUV™ units to conceal them from view.


Backfill around the HydroUV’s to their middle simply to stabilize them in a vertical position. Place the valve box over and around the UV’s (you’ll need to cut holes in the sides of the valve box where the inlet and outlet pipes are). Next, place a brick on the soil inside the valve box and install the HydroAir™ pump on the brick to keep it above the soil. In this case, the air tubing leads from the HydroAir™ pump to an Airstone contained inside the Aeration Tower™.


With the plumbing lines attached to the outside ports of the HydroClean™ Pond Skimmer, now you can connect the Custom CamLock Checkvalve Assembly (CVA) to the inside ports. This custom CVA provides an additional strainer before the pump and a backflow prevention valve that keeps the pump primed.


The Custom CVA attaches with quick and easy CamLocks.


Simply apply a bead of Silicone to the male section of the CamLock fitting and thread it into the Outlet Port of the HydroClean™ Pond Skimmer. Then, slip the female section of the CamLock over the male section and pull back on the Stainless Steel Levers. That’s it! You just installed the CVA and you pump plumbing is totally complete!


This photo shows how the main pump is connected to the HydroClean™ Pond Skimmer via the Custom 2″ CVA unit and he HydroUV™ System is connected via a 500 gph magnetic drive pump and 1″ union assembly. The pond is connected to the HydroClean™ Pond Skimmer via the Bottom Drain inlet pipe and the surface skimming inlet pipe. A ½” water line is also connected to the HydroClean™ Pond Skimmer to feed the internal Automatic Water Fill Valve.


The HydroClean™ Pond Skimmer is designed to give you the most design, plumbing, and installation options of any pond skimmer on the market. Notice the “clean lines” of all the internals of the HydroClean™ Pond Skimmer and how it easily moves away from the pond’s edge. This allows the HydroClean™ Pond Skimmer to attach to virtually any type of pond construction materials from liner, to concrete, to poly urea.


This photo shows the pump pulling water into the HydroClean™ Pond Skimmer via the Bottom Drain Inlet Port even before the pond is full enough to reach the skimming inlet pipe. Connecting the Bottom Drain to the HydroClean™ Pond Skimmer uses the pump’s suction power to draw sunken fish waste into the skimmer’s Black Knight Filter Brushes for easy cleaning and removal prior to being “ground up” in the pump’s impeller. This lowers the burden placed on the biological filtration stage so the filter can run more efficiently at scrubbing ammonia out of the water for healthier, happier Koi. If you chose the Optional Auto Fill Valve Kit, now is the time to install it.


Apply a bead of Silicone to the threads of the Auto Fill Valve and thread it directly into the Auto Fill Inlet Port inside the HydroClean™ Pond Skimmer.


Next, apply a bead of Silicone to the threads of the 1/2″ barb fitting and thread it into the outside threads of the Auto Fill Valve Port of the HydroClean™ Pond Skimmer. Then, push the 1/2″ water pipe onto the barb. The pipe and barb make a water tight seal without Silicone or glue. At the other end of your 1/2″ water pipe, attach the Brass 3/4″ Female Hose Thread by 1/2″ Barb fitting with the supplied Stainless Steel Clamp. Then thread the 3/4″ Female Hose thread to your standard hose faucet.


Backfill the HydroClean pond skimmer, the HydroSeive bottom drain pre-filter, and valve boxes with soil. Compact the soil as you backfill.



The soil placed around the HydroClean™ Pond Skimmer is then retained with decorative retaining wall blocks. You can use what ever retaining method you choose – rock, block, wood, or concrete. In this case, we chose blocks for their ease of installation and decorative look.


Next, dress up the look of the treated wood with Cultured Stone. Cultured Stone is lightweight, concrete manufactured stone. Cultured Stone is extensively used on home facing and fire places. It is easy to install and available in a wide variety of styles and colors.


First, attach a galvanized wire mesh – called “lath” to the wood using Stainless Steel screws. Then, apply mortar to the backside of the Cultured Stone and “stick it” to the lath. For this Koi Pond, we chose “Weather Edge Ledgestone” for its color, texture, and ease of installation. Since the pieces interlock together, no grouting is necessary.


The Cultured Stone and flower bed retaining wall blocks give the Koi Pond an elegant look that can fit nicely into any landscape or garden. Since the Cultured Stone and retaining wall blocks are available in so many styles and colors, this HBV Series Koi Pond can be customized to fit what ever garden style or tastes you have.


The HBV Series Koi Pond is the safest pond styles for Koi, and can also be made stunningly beautiful. All the mechanics of the HBV Series Koi Pond are completely hidden from view, but are still easy to access for routine cleaning, backwashing, and maintenance.


The HydroClean™ Pond Skimmer is hidden within the raised flower bed at one end of the Koi Pond.


The raised flower bed softens the look of the Koi Pond, and when planted with two trees as shown here – provides shade to the pond. In this case, the trees are planted on the south and west ends of this pond to provide late afternoon shade to the pond.


Being installed at our Flagship Store in Redmond, Washington – this Koi Pond also doubles as an additional Koi Retailing Tank. Like a Koi in this pond? Its for sale and can be yours! Additional morning and noon shade is provided by a couple of potted trees placed next to the pond.


Being installed at our Flagship Store in Redmond, Washington – this Koi Pond also doubles as an additional Koi Retailing Tank. Like a Koi in this pond? Its for sale and can be yours! Additional morning and noon shade is provided by a couple of potted trees placed next to the pond.


The use of an Aeration Tower™ saturates the pond water with oxygen, but doesn’t disturb the surface of the water so you can see the Koi better. A few Water Lettuce placed in the corner of this Koi Pond are held in place with string as to not end up in the HydroClean™ Pond Skimmer.


With this Koi Pond being partially above ground, you can experience the Koi up close. You can even sit on the ledge and hand feed the Koi!


Koi, flowers, and hidden mechanics make Russell Watergardens & Koi HBV Series Koi Ponds fun and beautiful.


HydroClean™ Pond Skimmers are safe for your lovable Koi as their is no need for weir doors that can trap Koi inside the pond skimmer. With a HydroClean™ Pond Skimmer on your Koi Pond, the Koi can swim into, and OUT OF the skimmer! Also, the HydroClean™ Pond Skimmer has no abrasive screws or hardware in which your Koi could harm themselves.


HydroClean™ Pond Skimmers can be remotely installed like no other pond skimmer on the market. This makes for much prettier ponds. In this photo, the HydroClean™ Pond Skimmer is installed 18″ back from the edge of the pond. Beautiful plants and flowers are planted between the skimmer and the pond.


Lovable Japanese Koi in this beautiful HBV Series Koi Pond and Russell Watergardens & Koi. Notice how the Cultured Stone makes the retaining walls of this Koi Pond very unique and beautiful.


The HydroClean™ Pond Skimmer is concealed within the raised flower bed on this HBV-21 Series Koi Pond.


While the HydroClean™ Pond Skimmer is hidden from view when viewing the Koi, it is still easy to access for routine cleaning.


Just as the HydroClean™ Pond Skimmer is hidden from view, the HydroBead Vortex™ filter and Hydro Centrimax™ pump are hidden within the gardens. The only item visible in this photo is the Aeration Tower™. It will be hidden as Clematis grows to cover it.


HydroBead Vortex™ filters and Hydro Centrimax™ centrifugal pumps are designed for outdoor use, and to blend “into” the garden. You can always install them under a deck, or in a shed of some sort – but unlike other systems on the market – you can install them directly in your landscape with minimal visual impact.


HBV Series Koi Pond Kits let you build safe, healthy, and beautiful Koi Ponds for you beloved Koi. You can follow the process we documented in the photos above, or feel free to modify any part to fit your tastes and styles. Our Friendly Customer Service Associates are here to help you every step of the way.


You’ve just learned how to build a Koi pond!