Sierra Water Gardens
Pond Building & Design

Click here for ideas and design for your water feature!

Follow Me on Pinterest


There are three basic requirements to keep in mind when designing and building your pond to ensure your long lasting success and enjoyment in the hobby. The pond must have crystal clear water so that you may see your Koi swimming and growing in a healthy environment, the pond must give protection and provide a safe environment for your Koi, and it must be as easy as possible to maintain.


Pond Size and Depth


Koi ponds vary greatly in size and dimension, but for residential installation we recommend a pond no smaller than 1,500 gallons and no larger than 15,000 gallons. Every pond has its “stocking density”, or a maximum occupancy of fish before water quality diminishes to unsafe and toxic levels, and if you build a pond that is much smaller than 1,500 gallons (7’wide x 8’ long x 4’ deep) you’ll only be able to keep a limited number of Koi in your pond. Also, a smaller pond doesn’t mean keeping smaller fish—a six inch Koi today will be two feet long in a couple of years.

On the other hand, bigger isn’t necessarily better. If your pond is too large it becomes difficult to maintain, impossible to catch fish and costly to treat. Also, in order to meet a minimum pond turnover rate of at least once every three hours, the water and energy demands needed to run the pond can add up quickly.

To keep Koi safe from predators that find a brightly colored fish a target too good to pass up, a minimum pond depth of three feet is needed. Also, as Winter sets in, the warmest water is at the bottom of the pond where Koi spent their dormancy. Depth is not only vital to the Koi to keep safe from predation and freezing water temperatures, but also to keep them physically fit. With a flick of the tail, a Koi can propel itself across the largest of ponds; but it is swimming at different depths, up and down, that allow Koi to grow quickly and gain lean muscle. Another reason to make the pond deep is because the pond will hold more water without taking up more room, and the larger the volume of water the long it takes to change in pH, ammonia, or nitrites.


The Shape and Contour of Your Pond

Ponds should not be irregularly shaped, like a puzzle piece; but rather like a kidney or bean shape so that there aren’t any “dead spots” in the water which act like debris traps. It is important that current flow easily and circularly throughout the pond.

The bottom contour of your pond is extremely important. The bottom and sides need to slope to one or more centrally located bottom drain. In this way, the pond is virtually self cleaning because all the sediment and debris that falls to the bottom will naturally be swept to this location for easy filtration.


Pond Placement


In the dry desert heat of Northern Nevada a pond situated in the shade is the best. Both flora and fauna in your pond need the sun, but high exposures can cause unrelenting algae problems and often raise the temperature of the water to unsafe levels. There are many natural and artifical ways to create shade above your pond, but beware of building a pond beneath a pine tree. The pine needles will pass through skimmer baskets and clog in your pump propeller.

Use a garden hose or extension cord to lay out the shape of your pond. It would seem to make sense to dig your pond in the lowest part of the yard, but because this is the place runoff irrigation water tends to collect, ponds will often become contaminated or flooded.

Place the pond skimmer opposite the waterfall so that the water current may naturally flow towards the skimmer. If possible, place the skimmer on the down wind side of the pond to catch the leaves on a blustery day.


Wanting a Koi pond with fragrant lilies and bushy marginals is not an unfair desire, but mixing plants and Koi can be risky business. If you place plants on a shelf so that they may thrive at the optimum water depth, what is often created is a perch for herons and raccoons to do their fishing.When Koi reach eight or ten inches in length they begin to forage through plants and tip over submerged lilies, causing a very dirty mess in your pond. And when plants die off during the fall, their decayed remnants often stay in the pond until spring, making pond cleaning a more demanding task.

Plants are not necessary to complete the pond cycle by consuming nitrates as the naturally occurring carpet of algae that grows on the sides of any healthy pond does that job. Additionally, if you salt your pond either for parasites or for string algae you will kill your plants as they cannot tolerate a salt level of .3% to .4%. An ideal marriage of Koi pond and plants keeps the planting area isolated from the pond, usually in the form of a bog serviced by a smaller pump or a traveler line of the main pump.

Hyacinths are one plant this is an excellent choice for a Koi pond. They multiply quickly, provided much needed shade for some ponds, and their roots acts as floating filters, so much so that they even need to be rinsed off occasionally!



Never place river rock or gravel in the bottom of the pond! Here’s why: the rocks act as a trap for any decayed material or fish waste. Aeromonas bacteria feed on this waste, and when it collects in between the rocks it provides a feast for a thriving colony of flesh eating bacteria in your pond which cause ulcers on your Koi. It would seem a good idea to make your pond look as natural as possible by lining the bottom of the pond with pebbles and stones, but, quite frankly, there is nothing natural about keeping Koi in an enclosed system in the backyard. The filtration that Mother Nature provides is always “flow through” whereby water enters and it exits, it is constantly being replenished. Our Koi ponds are like recirculating toilets and it is the primary task of the pond keeper and his or her filtration methods to remove the debris and waste from the toilet, known as “mechanical filtration”. Rocks make this job impossible by interfering with the performance of the bottom and making pond cleaning a futile activity.

Ideally, a Koi pond should be as smooth as a baby’s rump from top to bottom. If you use rocks, we recommend using the smoothest rocks you can find and only using them along the edges of the pond to help define its contours. Fish, when they flash or spook, will often rub violently against the edge of the pond. Should they cut themselves on the side of a rock, real medical problems could ensue.



Rubber Liner or Concrete?

Ponds constructed of a rebar frame and gunnite or shockrete have many advantages if constructed properly, but, if built with flaws, corrections can be a nightmare. A great Koi pond employs the same design elements as a swimming pool, with gradually sloping edges to a bottom drain, and future pond owners are able to work with the swimming pool builders to build their dream Koi pond. Concrete ponds generally run a higher pH for the first five years unless coated with a product such as Herco. It is also easier to install rock work and masonry to a concrete pond than it is than a liner pond.

Liner ponds are generally less expensive to install and are the preferred choice for “do-it-yourselfers” because changes and adjustments can be made. .45 mil. Liner can be difficult to work with and requires pleating to conform to the contours of the pond; but, once suppressed by the weight of 24,000 lbs of water, are hardly visible. When carefully installed, rubber lined ponds can remain leak proof forever and stands up to UV degradation. Rock work around the pond edges intended to hide the line can be a bit tricky as mortar does not stick to liner and waterfall foam does not last forever. It is also a good idea to add a base layer of sand and an “underlayment” fabric underneath the liner for added cushion and protection from roots below or jagged edged from above. If you’re adding larger boulders to the pond for decoration, add extra layers of padding and even a few liner scraps on top for peace of mind. In the name of resourcefulness we like to use old carpet padding (staples removed).


* The first installation method is the easiest but requires stable soil behind the liner. It is also the least attractive because the liner remains visible.

* The second method requires more labor, but the liner is kept hidden, rocks are kept to a minimum but appear to

extend to the depths of the pond.

* The third installation is for flagstone applications. The liner is contact cemented to the beam, and mesh wire is

anchored to the top of the beam and is used to keep the cement adhered to the liner.

Pre-formed ponds are not a good option if you are looking to keep Koi. They are not as versatile as liner, and more expensive too. Also, because our Sierra Nevada ground freezes to up to a foot or more in some locations, the expansion and contraction of the ground will sometimes crack these pre-forms.


Should I Take the Time to Install a Bottom Drain?

Absolutely! Because the majority of debris that is in your pond falls to the bottom the only way to have a consistently clean pond that is both safe for your Koi and nice to look at is to have a bottom drain. The term “bottom drain” does not refer to a literal drain that is installed at the bottom of the pond but rather a location from where your pump will pull water that is to be filtered and re-circulated back into the pond. Bottom drains sit within a half inch of the bottom of the pond and are generally installed through the liner or concrete. It is preferable that you run 3” to 4” ABS pipe from your bottom drain to accommodate for large debris, so simply placing a submersible pump at the bottom of the pond is usually insufficient, though the idea is the same and it works in a pinch.

There are a few different ways you can install a bottom drain:

The first is by gravity. This method requires that the bottom drain line be installed at an incline lower than the bottom of the pond to a pre-filter that is buried at the same water level as the pond. From here the water is pumped, generally via a sump, to the filter and then back to the pond. This is a good method if you use a gravel filter or any other filter that is cleaned only once or twice a year because most of the heavy debris such as leaves and algae will end up in this collection box before it gets to your pump strainer or filter. The down side of this method is that it generally requires a sump pump to drain it and demands the space to install a large pre-filter or settlement tank at ground level.

If you have a small pond that only necessitates the use of a submersible pump inside a skimmer box, then you may install the bottom drain line into the front of the skimmer box. On the inside of the skimmer box you can use a knife or ball valve to control the water flow from the bottom drain. This method of installation is very straight forward but can cause some problems as all of the waste that is generated through the bottom drain ends up in your skimmer first, causing the frequent removal and cleaning of any pre-filtration media you keep inside of your skimmer.

There is usually some trepidation about installing a large bottom drain line under the pond—and this is not without warrant. Should a leak occur somewhere in this line it is virtually impossible to get to it without tearing up the pond. Additionally, there are many ponds that are built without bottom drains and the owners are now realizing there is a great need for a bottom drain. As a result of this, “retro-fit” bottom drains are an emerging technology in the pond industry. Some can be equipped with up to a 4” pipe, but at Sierra Water Gardens we like the poured concrete drains that are heavy enough to stay in place at the bottom of the pond and fit onto 2” flex pipe that sits on the bottom of the pond and are generally serviced by an external pump.


Do I need to install a UV light?

Here in Nevada where the sun is bright and hot, pond owners can usually expect to have green water problems. Water that is pea soup green is caused by floating algae spores and there is no product you can use to treat this problem which is also safe for your Koi with the exception of a UV light. UV lights are sized depending on how many gallons pass through them per hour…what matters is how long the water is in contact with the light. The ultraviolet light clumps the algae spores together and they are then picked up by the filter. UV lights are rated as either “clarifiers” or “sterilizers”: a 57 watt UV will clarify, or clear up green water, a 6500 gallon pond with a turn over rate of once every two hours; and it will sterilize, or kill free-floating parasites, a 3000 gallon pond that cycles every hour. Because UV lights are expensive we don’t expect people to budget for them right away, but because you can expect green water, plan for a place to install a UV light somewhere down the road. UV lights are usually plumbed in-line with the piping but some skimmers do have places to install a light without discreetly and without slowing down the water too much.


Should I install an Air Diffuser?

Absolutely! Koi ponds can never have enough oxygen, and if you think that your waterfall provides a sufficient amount, be assured that this is never the case. Koi can’t live without it and algae cannot grow with it. Algae blooms occur in the warmest, least oxygenated parts of a pond. By utilizing an aerator, you maintain pond circulation and temperature while adding oxygen to aid the fish, ward off algae, and lift noxious gasses of decaying debris to the surface of the pond. Also, aerators are a 24-7-365 pond product. Keep them running during the winter to maintain holes in the ice! You can install a bottom drain with an air diffuser or tangential pond jets so that you never see an air hose, or, if you are retro-fitting your pond with one, they are rated in cubic feet per minute (cfm) and will work from small ponds and aquariums to large lakes.

What type of filter should I install?

There are two main components of filtration: BIOLOGICAL and MECHANICAL. Biological filtration is composed of the two types of nitrifying bacteria that convert ammonia to nitrites and nitrites into nitrates. Because they grow inside of the filtration media, you want to select a media that provides the most area for the bacteria to grow while allowing for maximum oxygenation. Mechanical, the second type of filtration, is the type that pond keeper’s need to concern themselves with. GET OUT THE GUNK! Filters come in an array of shapes and sizes, but the principle is the same: Water flows through a medium (filter mats, gravel, beads, lava rocks, bio balls, etc.) where the debris progressively gets trapped (and later washed out by you)


GRAVEL: Gravel filters are by far the cheapest filters to build as the price of a square yard of 3/8 inch pea gravel rarely exceeds $20. Gravel filters work by gravity, whereby the water is pumped into the bottom of the filter, it flows upward through the filter media, and exits through the top, falling into a pond. The primary purpose of a gravel filter is biological filtration…they are not easy to clean and are only cleaned once or twice a year through a “blow out” pipe built into the manifold. Gravel filters can be made in something as simple as a horse trough or large blue food-safe barrel, or built into the pond’s waterfall. Below is a diagram showing a design for a manifold out of which the water is dispersed, followed by a grate to hold up the media.



PRESSURIZED FILTER: A pressurized filter, sometimes referred to as a bead filter, combines both biological and mechanical filtration with the turn of the valve. Easy to clean in a suit, pressurized filters are filled with some type of filter media on which the bacteria grow, and, through the use of jets or a blower, are able to expel solid fish waste quickly and easily. They are serviced by an external pump and are able to be place long distances from a pond for easy hiding. Swimming pool filters should not be used because their mechanics are different and they utilize sand for media which is meant to filter oil, lotion, and hair, not mud and Koi waste.


What Size and Type of Pipe Should I Use to Plumb my Pond?

The size of pipe you choose to use is critically important. If the plumbing is too small it will restrict water flow dramatically. Blow is a basic guide for selecting tubing size.


Flexible PVC is the go-to type of PVC pipe used in pond building because it shapes to any contour, enabling you to run the water through a “sweep” rather than a “bend”, which doesn’t reduce water flow as much. When working around the filter and U.V. light, the more rigid schedule 40 straight pipe is the way to go.

Kink-free hose, used with barbed fittings rather than glued, is a good choice for small water garden features.


Pump Performance, Efficiency, and Placement:

“Head Height” is the term used to describe how many gallons per hour or minute a pump will discharge at a given height. For instance, a 3600 gallon per hour pump will pump 3600 gph unrestricted, or at zero feet of head. But, if your pumping the water to a 10 foot waterfall, that same pump will only discharge 2000 gallons per hour. So it is important to know the measurements of your pond to determine which pump is right for the applications. Additionally, the length of tubing is also an important factor. For every 10’ of run, or horizontal piping, you lose one foot of rise, or head height.

It is important to go with more pump than you think you’ll need. You can always choke down the flow of the water with a ball valve on the discharge side without stressing the pump. But, if you get a pump that will only meet the minimum requirements, you might be left with just a trickle for the waterfall and you cant add more pump!

If you are running an external pump, where you place it in relation to the water level is very important so that it maintains its prime. If you set the pump above the level of the pond, you will have difficulty priming the pump at first and will need to use a check valve on the intake line to keep water going in the correct direction. By placing the pump below the level of the pond, it will maintain its prime through flooded suction, whereby water, and not air, will always be flowing through the pump.


Max Water Flow (g.p.h.) Inside diameter of tubing

300 ½”

600 ¾”

1000 1”

1800 1 ¼”

2500 1 ½”

4000 2”

6000 2 ½”

9000 3”

12000 4”

Web Links Worth Looking At: