Koi Pond & Waterfall: Top 21 Most Asked Questions Answered

Question: What is the ideal depth for a koi pond?of their prize koi. A critter-proof pond is over 3 feet
Answer: In my experience of over 25 years, 4 to 5everywhere and has a raised deck 13" minimum over
feet is ideal. You need a minimum of 3 feet for koi fishthe water surrounding the pond. Raccoons cannot
for several reasons. Safety for fish from wadingswim and catch fish at the same time, and they or the
cranes they can't wade in 3 feet of water. Plus thebirds will not be able to reach the water.
water temperature in shallow ponds fluctuates tooQ I would like to have a koi pond but I live in Michigan
much with the changes in ambient temperature. Theand every year ponds and lakes freeze over. Will they
greater the volume of water, the longer it takes for thesurvive?
temperature to change. Warm water or fluctuatingA There are fish in those lakes you are talking about:
temperatures are unhealthy for fish.blue gill, bass, sunfish, carp, and they all survive. And
Q What is the ideal size for a pond?guess what? Koi are in the carp family. Koi were
A The ideal size would be determined by the size oforiginally raised for food in Japan. They would grow
your yard. Its size should be proportional to the size ofrice in the summer and then flood the rice patties and
the yard. Also, the larger the pond, the greater theraise koi in the winter, cutting holes in the ice to catch
maintenance.them for food. However, your pond must be 4 ´
Q What is your opinion on using a liner to construct ato 6 feet deep to ensure the water stays about 40 o
pond rather than using a hard molded or concrete one.the bottom. Turn off the waterfall and bottom drain,
A My recommendation is and always has been to usedraw water from the skimmer to keep the bottom still.
concrete. However, if you are on a tight budget or doPlace swimming pool solar blankets over the surface. If
not plan on living there for an extended period time, ayour pond is deep enough, you can let it freeze over.
liner would be recommended. In this case, you wouldHowever, you need to install a horse tank heater to
have to add a thin layer of mortar between the linerkeep a hole open in the ice to allow any ammonia gas
and soil to prevent tree roots, ground squirrels, rats,from rotting debris on the bottom to escape. If your
mice, gophers or chipmunks from compromising thepond is less than 4 ´ feet deep, take the koi
liner. The hard molded, preformed plastic pondsindoors for the winter and place them in a garage or
become brittle from the sun's UV rays in just a couplebasement tank.
of years. No good!Q Can I keep koi and goldfish together?
Q What type of pond filter do you recommend?A Yes, you can. They are both cold water fish and
A That cannot be answered simply because manymembers of the carp family. Most other cold water
factors are involved. Do you have an existing pondfish can also swim together, such as shubunkins, rudd,
with a submersible pump or above-ground pump?orfe, blue gill, mosquito fish, guppies, sunfish, bass, etc.
What's the volume of the pond? Do you have fish, andHowever, only in deeper ponds where the mean
if so, how many? What size plumbing pipe is beingtemperature is 65 degrees or less on the bottom for
used? This is so involved, I have devoted an entirebass, sunfish and blue gill.
chapter in my construction manual to the subject. IQ Should my pond have a bottom drain?
have an 8000 gallon pond with above-ground pumpA First of all, a bottom drain is essential for a healthy
and I use a pressurized biological bead filter. It takes 2pond. However, if it is exposed and the suction is
minutes to back flush with the turn of a handle andstrong enough, turtles or fish can get stuck to it and
keeps my pond crystal clear.not be able to get loose. Therefore, two drains should
Q I have tons of algae hanging from the rocks in mybe hooked in series to relieve the pressure between
falls and growing in clumps in my hand. What can I dothem, just as in a swimming pool. Bottom drains draw
to get rid of it?falling waste from the fish before it reaches the
A When the first Polynesians settled in Hawaiibottom, keeping it clean. Areas where it does build up
between 300 and 600 AD, they were probably verycan be swept to the drains for easy cleaning. If you
annoyed by the aggressive, wild, pervasive taro plant,are using a submersible pump or pulling the water from
just like you are your algae. They tried to chop it down,a skimmer, water is not circulating properly on the
burn it, stomp it, but to no avail. It just came back, sobottom of the pond. That is where rotting debris is
they eat it, and still do to this day. In fact, it's a stapleproducing ammonia and other toxic gases.
like peanut butter is to some Americans. Just kidding!Q My pond water is very clear, but my fish are dying.
However, if you told me it was watercress I wouldWhat is wrong?
suggest eating it. Many pond stores will try to sell youA Drinking water might taste good, smell good, and
a very expensive algaecide to solve your problem, butlook clear. But some of the most toxic chemicals that
all you need to do is increase the salt content of yourare known to cause cancer are colorless, odorless
water. Some experts recommend one pound of rockand tasteless. I recommend that you purchase a test
salt to every 100 gallons of water. This will not hurtkit form a pond store and check your water regularly.
your fish; in fact, it will help to produce a healthy shineNitrates, nitrite and ammonia are all detrimental to fish.
coat. However, it will harm most of your plants if youAmmonia and nitrite can, at high levels, be fatal to fish.
apply that dose all at once. Plus the dead andThese substances are dissolved in the water and
decaying algae will deplete the oxygen and this willconsequently are impossible to detect by the clarity of
harm your fish. Apply it slowly over a week or two,the water and they can break down the fishes'
and be patient. It takes longer to kill it this way, but yourimmune system.
fish will appreciate it! This topic is also a chapter in myQ What type of filter do you recommend?A For any
construction manual.pond over 1000 gallons, I recommend a pressurized
Q Should I keep salt in my pond on a regular basis?biological bead filter that can be back washed. I have
A If you maintain a specific gravity of 1.000, your fishused Aqua Ultraviolet Ultima II filters for years. Most
will be less susceptible to ulcer and fin rot. And you willlarger pond suppliers carry them. Their filters range
keep the algae from getting out of control.from 1000 gallons to 10,000 gallons. Up-flow and gravity
Q I am considering building a waterfall between myflow filters require regular cleaning, which is a filthy job.
house and my neighbor's against the fence. Will theThe filter media is packed with stinky, putrid fish waste
sound of the falls annoy them if I let it run 24 hours aand decaying pond scum. As you handle the filter
day?screens, media, scrubbers, etc., you will have little white
A The sound generated by a waterfall is called whitefeces-eating worms that are 1/16" long crawling on
noise, which is very relaxing and soothing, not annoying.your hands and arms. Not to mention the noxious smell
I have several hundred clients who leave their fallsthat burns your eyes and lungs.
running 24/7 and none have ever had a neighborIt cost pennies on the dollar to make, yet dealers
complain. In fact, they all appreciate the fact that theycharge a fortune. You pay the price for the filter and in
did not have to spend the money to enjoy the sound.the time it takes to maintain it you pay an additional
Q How many koi fish can I put in my pond?cost for your time maintaining it. With a pressurized
A The amount could range from 150 to 250 gallonsfilter, it only takes the turn of a handle for 2 to 3
per fish. If you are starting out with small 6" to 8" longminutes and the filter is clean. The waste water is not
koi, they can reach 2 feet in three years, depending onwasted either. You can water your plants with it using
how much food and how often you feed them. Theythe discharge hose. If you can imagine, that brown,
could even grow to over 3 feet long! Thecolored, stinky water is packed with nitrogen. It's better
overcrowding of fish produces stress and a lot ofthan Miracle Grow T.M. I have used my 6000 gallon
waste material. It can reduce the health of the fish andUltima II for over eight years and it works as well now
result in various diseases. Also, a less crowded pond isas they day it was installed. Happy, happy fish!
more pleasant to look at.Q How much does an average pond cost?
Q Do I really need a filter in my pond?A What is average? It depends on whether you are
A Not in every case. If your pond is small and youtalking about a liner pond or a professional concrete
have any guppies or mosquito fish and adequateand rebar pond. A typical liner pond can be 6 feet by 8
water plants covering 1/3 to ´ of your pond, yourfeet, and depending on who is installing it, could cost
pond will clean itself by means of the nitrogen cycle.between $2,500 and $3,500. The other dimensions are
The biological aspects of pond chemistry is wellpretty much proportionate. Liner ponds are susceptible
covered in my waterfall and construction manual.to leaks from punctures, gophers, and rats, etc.
Q How long do koi fish live?Concrete ponds last for decades and on the average
A The average life span of koi in Japan is 70 years.cost only 20% more than liner ponds.
Some have been known to live to 100 or more, suchQ My pond is green and I can not see my fish. What
as the legendary Hanako, alleged to have lived forshould I do?
over 200 years. Unlike the amazing results of theA Your challenge is algae (suspended planktonic
meticulous care the Japanese give their koi, Americanalgae), which does not directly hurt the fish. However,
koi live a fraction of that time, usually due to neglectalgae gives off oxygen during the day from
and lack of care or proper environment.photosynthesis. But unfortunately, it uses up oxygen at
Q How can I protect my koi against predators?night. In addition, it is unsightly and blocks the view of
A Unfortunately, most people that come to me arethe fish. You can increase the salt content or install an
frustrated people who already have a pond or aultraviolet light, which not only kills spore algae but kills
rather poorly planned pond. If your pond is shallow, lessthe bacteria that causes the water to become murky
than 3 feet, or has a shallow end, the raccoons,and stinky.
coyotes, cranes, egrets, etc. have easy access toQ I heard that UV light will also kill the beneficial
your fish. You may think your fish are safe becausebacteria. Is that true?
you have a deep end for the fish to retreat to. Well,A If I say "No," I am calling many so-called professional
you and your fish are dead wrong. A crane will standexperts liars. So I will put it this way. All the beneficial
perfectly still for 10 to 20 minutes waiting for the koi topond bacteria such as aerobic or anaerobic bacteria,
forget he is there. Some will regurgitate chum into thenitrobacter, etc., reside in the filter or in the decaying
deep pond, luring the fish to the surface. Your onlydebris at the bottom of the pond. They aren't floating
solution is a net, or try the crane statue, scarecrow, oraround in the pond. Bacteria and algae containing
high-frequency sound emitters for smaller animals.pathogenic disease are, and as they pass through the
However, one of my clients watched a crane landUV light, they are eradicated.
next to his crane statue. While the scarecrow wasQ Do I need a waterfall for my pond?
pelting him with a stream of water, it snatched up one