In This Chapter
- Thinking through pond problems and options upfront
- Choosing your pool materials and shape
- Settling on the perfect location for your pond
- Filtering out your choices
Koi fanciers joke that there are
three certainties in life; an outdoor koi pond is one of them. A garden pond
adds a whole new dimension to koi-keeping. Only small fish can stay indoors, and
as they outgrow their tank, you have to find something to do with them. A pond
offers the option of keeping koi long term so you can watch them grow and begin
to understand their individual ways. In short, it allows you to make real pets
of these fascinating fish. If you’re serious about koi and want to give them an
enriching environment, then a pond is really the only way to go.
This chapter helps you decide
whether a pond is the logical next step for you and, if so, how to plan for
one. We discuss the planning process, including where to locate your pond and
what options you have for size, style, and materials. (We cover the supplies to
run the pond in Chapter Making
Sure Koi Are Right for You.) To give you an accurate picture, we also examine
the legalities of pool construction as well as the potential problems you may
encounter.
Considerations to Toss Around Before You Dig
In making a major decision, it’s
a good idea to check out all the angles and consider the consequences of that
decision. But a koi pond? That’s easy enough. It’s a simple structure with a
simple purpose. How complicated can this choice be?
This section helps you answer
that important question by highlighting three potential problems that may
affect your choice.
Then we take a look at your
existing pond or pool so you can decide whether you can adapt it for your koi.
Avoiding potential problems
Adding a koi pond is much more
detailed than simply digging a hole in the ground, putting in water, and
allowing the koi to swim to their hearts’ content. When you’re contemplating a
pond, consider two potential problem sources — small children’s safety and your
neighbors’ concerns — before you even start digging.
Safety is key: Small children and small animals
Koi ponds are irresistible to
adults and children. Who doesn’t love those big, friendly fish that come
right up to the water’s edge at feeding time? Unfortunately, unfenced koi ponds
and small children just don’t mix. Each year children drown in water as shallow
as a few inches, so a pond of any size is a major hazard.
Warning!
The area around the pond and any protruding rocks can be wet and slick due to algae; both adults and children can easily slip and fall. If the fall results in the person becoming unconscious, a drowning can easily result.
Also consider the dangers for the
mentally challenged or physically infirm persons who may gain access to the
pond. Although pet dogs and cats are usually sensible around water, tortoises
and guinea fowl have been known to drown even in shallow outdoor ponds.
Tip
Whether the safety issues are yours or a neighbor’s, don’t quibble. Add a fence, even if it isn’t required, and tell your neighbors why you’re doing it. That way you all know you’ve done what you can to prevent the unmentionable.
Considering your neighbors’ concerns
Next-door neighbors have a vested
interest in your yard, or they think they do. This attitude is especially true
if they have safety concerns (see the previous section). Your neighbor may also
be worried that the pond can become a breeding ground for mosquitoes (consider
the media attention given to the West Nile Virus).
Occasionally ponds draw raccoons,
ducks, or other animals that may annoy neighbors — even loud frog choruses have
been a source of complaints. When you tell your neighbors you’re thinking about
building a koi pond in your yard, you can remind them that the pond will be
behind a fence. If the circumstances were reversed, you’d appreciate the
heads-up.
Cutting your way through the red tape
If you’re seriously considering a
koi pond, get ready to jump through some hoops at your city or county municipal
building. Before you can break ground, you have to obtain the appropriate permits
from your local municipality.
How to acquire the right permits
To ensure that you cover all your
bases and don’t have any problems with your city or county, you first have to
make an important choice:
- Hire a contractor to build the pond for you. One of this person’s responsibilities is to obtain all the necessary permits. (Check out Chapter Making It Pretty: Landscaping the Pond for more info on hiring a contractor.)
- Do it yourself. If you build the pond, you need to acquire all the necessary permits and file the appropriate paperwork.
When going it alone, keep these
important steps in mind for acquiring the permits:
1. Call or e-mail your municipal planning and zoning department and the building department.
In some areas, these departments go under different names or their functions are combined. Usually a zoning department is a good place to start. If your city or county has a general help line (for example, 311 in New York City), you can check there for specifics on how to proceed.
Ask whether your city or county has code restrictions on ponds in general, on their size or depth, and on their placement. (For example, does it need to be set back from property lines? Can it be in the front yard or backyard?) If you need permits, ask what kind and what their costs are.
2. Keep a log of whom you talk to, the date you talk to that person, and what he says.
Keeping track of which department needs which permit can be confusing; when you’re talking about a $5,000+ project, you’re talking about real money.
Remember
Dealing with city or county regulations isn’t too expensive. Permits are generally based on the estimated cost of the construction, usually $65 to $125 each. Your only real expense is your time, but it’s time well spent if you can avoid cease and desist orders (C and Ds that your municipality issues in response to projects without permits), expensive fines, and liens. Municipalities can and do play hardball on construction regulations.
Why the permits are important
Getting the appropriate permits
(and the ensuing inspections) protects you in three ways:
- If someone in your neighborhood decides that she doesn’t like the idea of a pond — in your yard or anywhere in the free world — having the necessary permits in your hand saves you a lot of trouble.
- The inspections that are part of the process assure everyone that you’re building to code. In addition, this built-in safety factor can pretty much guarantee that you won’t get electrocuted by your wiring system.
- If you decide to sell your house, any construction without a permit (even on something as elegant as a koi pond) can be cause to void a sales contract. It’ll also make you look (and feel) like a cheap schmuck.
Your local city or county
municipality rep can tell you which permits are required. Typically, you need
an electrical permit for your pump and filters and a plumbing permit for water
and gas lines. You may or may not need a fencing permit, but a fence is
generally a very good idea.
Tip
Some cities suggest that you include a site plan with the permit applications so the issuing officer has a better understanding of the construction. You can sketch this plan out yourself, or you can use a software program (very reasonably priced). The program lets you enter your yard shape and dimension, your pond shape and dimensions, and various design elements. You end up with a printout of your pond and its location in your yard. Very cool.
What if you already have a pond (or pool)?
If you’re seriously considering a
koi pond for your yard and already have a shallow goldfish pond (or a cement
hot tub), you may be in luck. You can probably adapt the goldfish pond to a koi
pond by digging it deeper or by adding a larger and deeper pond next to it and
knocking out the intervening wall.
The real advantage of making a
pre-existing shallow pool much deeper (a minimum of 4 feet is recommended) is
to keep koi in a relatively small space. Plan to add plumbing for the bottom drain(s)
and a raised lip (if the pond doesn’t already have a ledge). See Chapter Making
It Pretty: Landscaping the Pond for
an illustration of a raised lip.
Can you turn a swimming pool into
a koi pond? In a word, yes, but you need to make a few changes. You need to
- Remove the ladder(s) and fill the holes left by the screws
- Give away the container of chlorine
- Round the corners of the pool
(Check out Chapter Making
It Pretty: Landscaping the Pond for
instructions on converting a pool into a koi pond.)
Deciding to take it indoors: Knowing what you’re taking on
If you’re seriously considering
an indoor home for your koi, the location of your koi’s indoor home is an
important but often overlooked consideration. It needs to meet several
criteria:
- The floor below the pond or aquarium must be suitably sturdy. Even the smallest possible aquarium, 50 gallons, weighs in excess of 600 pounds when filled with water and gravel.
- If you use an aquarium stand, it must be level and topped by a sheet of cork or foam. Even minor pressure points can cause a crack to develop.
- A source of electricity should be close by. Ideally, the outlet is off to one side so accidental spills can’t touch it.
- You must allow space for your filter. Otherwise, you’re in big trouble.
- Your koi’s home should be in a quiet location away from windows.
Fish may react to water-borne vibrations from televisions and slamming doors. Consider also whether the noise from the filter may disturb your home’s residents; plan accordingly.
Sunlight through windows can foster the growth of algae and raise water temperatures in a nearby aquarium or pond.
- You may need flood insurance. Considering the damage that the water from a 200-gallon tank can cause, flood insurance may be a wise choice.
Planning for weather changes with an outdoor pond
A pond heater and cover can keep
your koi at least marginally active during cold weather. You can buy the parts
separately and install them yourself, or you can purchase self-contained units
that hold the gas boiler, circulator, expansion tank, temperature control, and
temperature sensor all in one. You may want to retrofit one of these units into
your current filtration system, but consider adding a single custom-built unit
to take care of UV sterilization, filtration, and heat. It may be well worth
your time and money.
In the heat of summer, you can
cool a pond with water movement, a waterfall, a water fountain, or trickling
water down a flume (add bog plants to a flume to take up nitrates). As the
water moves and is exposed to air, evaporative cooling takes place.
Looking at Your Pond Options
When planning your koi pond, you
have many options. However, the three most common types of designs are concrete-block
wall ponds, liner-alone ponds, and concrete-block walls with liner. This
section looks more closely at these three types to help you decide which one is
right for you and your koi. After you decide, check out Chapter Making
It Pretty: Landscaping the Pond for the
building specifics on these ponds.
Choosing your material
Koi ponds have come a long way
since the first mud ponds in Japan, and you need to decide from the beginning
whether you want a concrete pond or a liner pond.
Concrete ponds
Concrete ponds are a serious
investment, but many koi-keepers feel that the advantages more than offset the
extra cost. Consider the following pluses:
- Largely a one-time expense
- Instantly beautiful; small additions (such as a marble, tile, slate, or brick pond edge) make them even more visually appealing
- Durable (can’t be punctured by the weight of the water pushing against stones or buried sticks); cracks can be patched
Because concrete ponds are rigid
systems, they have to be strong enough to deal with frost heaves and mobile
soils (like sugar sand or clay). You can’t scrimp with a concrete pond, so
you’ll want to budget for the raw materials (the concrete and rebar) from the start.
In cold climates, the concrete needs to be at least 6 inches thick and
reinforced with wire mesh and rods.
Remember
Taking a long-range view, you can transform your concrete pond into a swimming pool by simply changing the color of the interior coating and switching to a different filtration system. This is a practical alternative if you ever move or decide that you no longer want to take care of koi.
Liner ponds
Liners are made from flexible
polyvinyl chloride (PVC). Although the liners are available in several
thicknesses, the minimum for pond construction is 20 millimeter, single ply. Be
sure that the liner is rated fish grade because there are several types
of flexible PVC and some are toxic to fish or plants.
Tip
In regard to durability, 20 millimeter PVC has a lifetime of approximately 10 years, but 32 millimeter PVC can last 15 to 20 years.
Technical Stuff
Butyl rubber liners aren’t very common in the United States, but they’re well worth searching for. Long popular in Europe, butyl rubber liners are 30 millimeters thick, are unaffected by sunlight, and can last 50 years or more. However, butyl rubber can cost up to twice as much as PVC and is more difficult to repair.
Liner ponds are by far the most
economical of all pond types because you essentially have no assembly work.
Consider these other advantages:
- Placing a liner takes a bit of work, but it’s still faster (and easier!) than building a concrete pond.
- Liners are usually one piece (which lessens the chance of a leak), but you need to install them carefully to minimize folds and areas of stagnant water, which create anaerobic pockets. Fresh, oxygenated water can’t circulate to these pockets, so harmful anaerobic bacteria (those that can’t live in the presence of oxygen) take hold, causing foul odors and decreasing the water quality.
- Although sunlight hastens the breakdown of a liner, the liner membrane isn’t typically exposed to sunlight.
- If the liner springs a leak, you may be able to patch it or drain it and lay a new liner atop the old one.
Liners do have a downside: Over
time, the surrounding ground tends to shift, causing the liner to shift as
well. Those neat vertical sides become a bit less vertical. Although this
sagging isn’t obvious to non-koi people, it can drive koi purists nuts. For the
second go-round, many owners install liners over rigid concrete walls. These
second ponds are almost always bigger and (sigh) better.
Concrete ponds with a liner
Concrete ponds with liners have
concrete block walls. The walls and the pond’s bottom (which isn’t concrete)
are covered by a liner. These ponds combine the beneficial features of both
liner ponds and concrete ponds and fall somewhere in between in terms of
expense and difficulty of installation.
A good design now makes a difference down the road
As with most endeavors, building
a koi pond properly from the start is easier than fixing problems later on, so
consider your options carefully before beginning. Lay out several shapes with a
garden hose, and view them from all possible angles (including your home’s
windows) that may face the area.
Consider also the depth of your
interests — if you know you’re a fish fanatic, then you may as well build the
largest pond within your means. If you tend to lose interest in hobbies
rapidly, then a simple pond may be your best bet.
Before buying materials, consider
such points as your soil and your yard’s slope. Will rocks or roots limit your
pond’s depth? Does the slope favor one shape over another?
Why pond depth is important
Koi are big fish. They need to
swim not only forward but also up and down in varying depths of water. A pond
that’s at least 4 feet deep provides the vertical range of motion they need.
The depth also helps stymie potential predators, such as long-necked blue herons
and grabby raccoons.
A deeper pond also has a more stable temperature. It stays cooler in summer and warmer in winter (this is important if you’re in the northern latitudes and plan on heating your pond). A 6- to 8-foot depth is the maximum that you — and your koi — will ever need.
Selecting the appropriate size
Remember
The wider the koi pond, the more koi you can put in it. However, you need to consider practical upper and lower limits before you decide on the size of your pond.
The smallest pond with enough
space for growing koi (and they all grow from 3 to 6 inches a year) is about 6
feet wide, 9 feet long, and 4 feet deep. A pond this size holds just over 1,600
gallons, which just happens to be your target gallon figure. Note: Although
you can say your pond holds 1,600 gallons in discussions with other people,
koi-keepers modestly round the size of their ponds to the nearest 500 gallons.
So in conversations with other koi-keepers, your pond holds 1,500 gallons.
How do you know how many gallons
fit into any given pond? Follow these calculations:
1. Determine the rough dimensions of your pond.
2. Multiply the length times the width times the depth.
3. Multiply that total number times 7.48 (the number of gallons in a cubic foot of water).
For example, a pond with a water
area of 8 feet x 7 feet x 4 feet is 224 cubic feet. When you multiply 224 by
7.48, you know the pond can hold 1,675 gallons.
Tip
Be sure you fill the pond to the actual depth that you figured. Most ponds have about 6 inches of freeboard (the distance between the water’s surface and the top edge of the pond), so a 4-foot-deep pond may only have 31⁄2 feet of water.
Remember
The shape of the pond affects the formula you use to figure the number of gallons the pond holds. For example, a circular pond uses the area of a circle (π × radius, squared) multiplied by the depth, multiplied by 7.48. So, for a 4-foot-deep circular pond with a 10-foot diameter, the formula is
Gallons = (3.14 × 5)2 × 4 × 7.48
= 246.49 × 4 × 7.48
= 7,374
Opting for a simple shape
Carefully consider the shape of
your new pond. The KISS principle (Keep It Simple, Sweetie) can help — not
because of your pond’s
Remember
For filtration efficiency, the simplest and most efficient pond shape is round with a funnel-like bottom leading to the filter drain. However, this isn’t very attractive. After your friends realize that the pond resembles a simple funnel, you’ll never hear the end of the jokes. Nevertheless, you can build a gorgeous, efficient koi pond and still incorporate the design elements that make a round pool so workable.
If you’re happy with plain-Jane
aesthetics and ease of care, another good shape is a simple rectangular or
oblong pond. This shape is easy to keep clean because
- It’s big enough to locate two filter drains along the midline.
- You can angle the water returns to nudge crud such as fish waste and dead leaves to the center of the pond.
- The pond has no dead areas (poor water circulation) because nothing stops the water from flowing.
Where to Dig Your Pond — Location, Location, Location
If you decide to build a pond,
place it where you can enjoy it the most. Most people prefer a tranquil place
in their backyard so they can easily view it from a window or back porch. Other
people take pond visibility to heart and place their pond both indoors and
outdoors (see Chapter Keeping
Koi Inside for more info on this variation).
Keep in mind the following
potential locations when determining the perfect place for your pond:
- In the full sun: A pond in full sun is heaven for algae, so you need to pay attention to the filtration system and the UV sterilizer. Your pond design should incorporate some rocky overhangs or other shaded spots for the koi because they need shade, too. A cloth- or vine-covered pergola over one end can provide a respite for koi and koi watchers.
- Under a tree: A pond beneath a tree is going to have pH and leaf or pine-needle challenges. The leaves fall into the pond and start to rot, causing the pH to become acidic. A good pond skimmer that has a pump and filter media can catch some of the leaves, but you still need to net leaves daily.
- Next to trees: Trees next to a pond present another problem. Tree roots can tilt sidewalks, pierce pond liners, and crack a cement pool. (Yes, you can patch liners and seal cracks in a cement pond yourself; see Chapter Maintaining Your Pond.)
- Next to a house or garage: A pond that’s under the edge of the roof overhang (where rain can fall into the pond) has a dramatic spike in pH after a rainfall. You need to monitor the pH. (You can buy an easy kit for this, or you can buy a pH pen. See Chapter Maintaining Your Pond for more on this tool.) Count on changing 10 percent of the water after a heavy rainstorm to keep the pH where koi like it (about 6.8 to 7.7).
- Near your neighbor’s yard: If your neighbor raises prizewinning roses and frequently uses spray insecticides and fertilizers, you may want to rethink placing your pond next to her yard. Place your pond at least 4 feet from a property line so it’s beyond the range of any incidental fertilizer or insecticide spraying. You can also check the direction of the prevailing wind (if there is one) and then locate your pond so your neighbor is normally downwind.
Finding the Right Filtration System
Unless you have a natural stream
flowing through your yard, you need a good filtration system to keep koi alive
and healthy. Filtration isn’t just an aesthetic consideration — it’s also a
necessity for maintaining the water quality your fish need. The movement of water
returning to the pond from the filter also disturbs the water’s surface,
causing its oxygen content to rise. Fish in poorly oxygenated waters rapidly
become stressed and die.
Koi are large, active fish that produce copious amounts of waste and use up lots of oxygen. Ideally your pump and filter need to process the total volume of the pond at least once every two hours. Natural systems (ones that rely on plants for oxygen and snails to recycle waste products) are doomed to failure unless you maintain very small fish in very large ponds.
This section looks more closely
at the importance of a filtration system in your koi pond and points out the
critical elements of a good system.
How a filtration system works
A filtration system for koi is
mechanical (straining out the solid and semisolid matter from the water) and
biological (removing the dissolved ammonia and other chemicals that fish
excrete). The system works in tandem with the pond skimmer, which removes
leaves and pond scum. As the filtration system pulls water from the bottom of the
pond, the skimmer pulls water from the pond’s surface.
Pond filters are either
above-ground units or gravity-fed units below the surface of the pond.
- Above-ground filters: These filters (about the size of a garbage can) are single or multiple units that sit directly on the ground, adjacent to the pond. They’re fed by a water pump that pulls water from the pond via a flexible rubber or PVC pipe. (You’ll need to dig a trench from the pond’s external drain pipes to the filter and construct a brick or stone-lined pit in that trench for the water pump.)
Although the pumps for the above-ground filters are submersible and you can conceivably place them in the pond, you don’t really want to do that. A pump outside of the pond is infinitely easier to service or replace if a problem occurs.
- Gravity-fed filters: These pond filters must be lower than the surface of the pond. Usually these filters are three separate chambers in a brick- or concrete-block-lined pit that’s adjacent to the pond. The water pump is located between the last chamber and the pond, taking the clean water from the filter and pushing it back into the pond. These pumps use less power than pumps for the above-ground filters, so they’re also more popular with koi owners.
Regardless of which filtration
system you use, you can decide where and how the water re-enters the pond. Some
people direct the water through a waterfall, through a shallow plant bog with watercress
or other plants that consume the nitrates, or through directionalized outlets.
(Bonus on the outlets: Some koi like swimming against the currents that the
outlets set up.)
The next two sections introduce
the two basic types of filtration systems.
Standard filter system
This traditional filter system
(see Figure 6-1) divides the mechanical and biological filtration components.
The filter may have either two mechanical and two biological components, or
three mechanical and one biological component. The mechanical component consists
of two chambers:
- The settlement chamber pulls in
pond water so solids and semisolids can settle to the bottom.
- The second chamber pulls the
first-stage clean water from the top of the settlement chamber and strains
smaller solid pieces of waste via interlocked brushes or a series of fiber
mats.
In the third or fourth unit (a
biological filter), convoluted plastic balls or PVC turnings provide surface
area for aerobic (friendly) bacteria. These bacteria require an
oxygen-rich environment, which the movement of water over the plastic or PVC
material provides. (Aerobic bacteria are a critical part of the filtration
process because they consume ammonia and nitrites in the water and convert them
to less toxic nitrates.)
The clean water that emerges from
the biological filter goes through the water pump and back into the pond.
Figure 6-1: A standard
pond filter, with mechanical and biological filtration components.
The bead filter
The bead filter combines both
mechanical and biological functions in a single, undivided unit (see Figure
6-2). This filter pulls water into a chamber that’s half-filled with floating
plastic media bits (or beads) that provide surface area for the growth of
friendly bacteria. As the water travels through the beads, the solid and
semisolid materials are filtered out. At the same time, the bacteria convert the
ammonia and nitrite to nitrate. The clean water is then channeled to the pump
for return to the pond.
Figure 6-2: A bead filter.
Choosing the right features for your system
Your filter subsystem needs to be
large enough to circulate and clean the pond water at least once every two
hours. A 1,500-gallon pond needs a
filter with a 750-gallon-per-hour (gph) capacity,but you won’t be sorry if you
buy one with a 1,500 gph capacity. The more often the water is circulated
through the filter, the cleaner
Larger filters are, of necessity,
powered by stronger pumps, which in turn cause greater turbulence as the water
is returned to the pool, allowing more oxygen to mix in with the water. This
feature is an important consideration for large, active fish — most especially during
the summer when the warm water holds less oxygen than cold water does. Plan to
install an appropriately large filtration system when you set up your pond, even
if the koi are small. If all goes well, they’ll grow and may soon over-tax a
small system.
When you’re comparing filters,
check out the surface area of the biofilter, the section that acts as
home to the aerobic bacteria. Because this component needs a lot of
surface area to make the water clean, you’ll find the better filters generally
have more surface area.
You can also purchase some
add-ons to a basic filter system, all of which make your koi more comfortable
and ease your work and worry load. Some extras include the following:
- UV sterilizer: This add-on between the filter/water pump and the outflow pipes is a self-contained unit that uses UV light to kill single-celled organisms like algae and protozoans in the water. (The filter can’t get these because they’re too small.) Eliminating these plant forms avoids the pea-soup syndrome.
- Pond heater: For ponds in northern climes, consider adding a pond heater. Koi can overwinter in northern areas like Detroit, but their survival factor goes way down if your pond isn’t deep enough or if the weather warms and then takes another nose dive. Unless you heat your pond, expect to lose a few koi at the end of every cold season. A gas- or electricity-powered heater is plumbed between the filter and the pond.
Warning!
Don’t spend your money on an all-in-one pump and filter that sits on the floor of the pond and plugs into a nearby electrical outlet. These units may be okay for a garden pond, but they’re awful for koi because
- They don’t have much cleaning capacity.
- The filter material quickly clogs.
- You have to remove them from the pond and disassemble them in order to clean them.
- Hoisting the water-and-sludge-filled filter out of the pond and then hosing off the components is a wet and messy chore.
- A submerged electrical pump is a short waiting to happen.
The cost factor: What does a pump cost to run?
When figuring out which
filtration system to purchase, you also want to consider the cost of running
the system. And because the pump needs to run all year, your costs also run
24/7/365.
To figure the cost to run a pump,
follow these steps:
1. Note the number of watts the pump uses.
For example, a pump can use 350 watts per hour.
2. Divide the watts by 1,000 to determine the kilowatts.
For this example, divide 350 by 1,000 to get 0.35 kilowatts per hour.
3. Take the number of hours in a year (365 days times 24 hours) to figure out how many kilowatts your pump uses in a year.
For this example, 0.35 × 8,760 hours = 3,066 kilowatt hours.
4. Take what you pay for a kilowatt.
Check on your energy bill. If you can’t find the info, call your electric or gas company. In 2005, the national average was 9.44 cents per kilowatt per hour.
5. Multiply the cost of kilowatts per hour by the number of kilowatt hours your pump uses per year to find the true cost to run your pump.
For this example, you pay 9.5 cents × 3,066 or $291.27 per year to run the pump.by R.D.Bartlett and Patricia Bartlett
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