In This Chapter
- Managing the equipment
- Striking a chemical balance
- Changing the water: Quick fixes
- Adjusting for temperature changes
- Protecting your koi
- Manning (or womanning) the pond all year round
You’ve gone to considerable time
and expense in designing and constructing your pond. Now that the pond is ready
and a half-dozen test koi have moved in, you invite some friends and neighbors to
celebrate with a barbeque cookout. Everything’s perfect.
But the next day you step
outside, look at the pond, and wonder, “What do I do now? Can I keep it going?”
Taking care of a pond is like
taking care of any complex organism. As long as you follow the rules, are ready
for a few exceptions to those rules, and pay attention to pond chemistry, you
and your koi are headed for a long, happy association. This chapter helps you maintain
your pond year-round by walking you through the regular, routine tasks and
explaining how the seasons affect pond care. We also guide you through the
basics of water testing and how to interpret your results.
Maintaining Your Equipment
Table 9-1
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When to Replace Your Pond Equipment
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Item
|
Replace at
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Water pump
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3 years
|
Filter
|
2 years
|
Air pump
|
5 years
|
Air hoses
|
Replace when you replace your air pump
|
Liner
|
20 years
|
Concrete
|
Essentially never, barring frost heaves or tree
root incursions
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Testing for Proper Water Chemistry
You can’t tell whether the
chemistry in your pond is right simply by looking at the water. Even if it
looks clean (koi-keepers use the term gin clear), the water can be laden
with bad components, like ammonia and nitrites, and shy of critical elements,
like oxygen. So even though your filter and water pump, air pump, and pond
skimmer are working together to rid the pond of the physical and chemical waste,
you need to monitor the water quality to make certain your equipment’s doing
the job right.
All you need is a pond
thermometer and two or three water-testing kits. You need to test for ammonia,
nitrite, salt, pH, dissolved oxygen, and chlorine/chloramine. Note: You
can buy multitest kits that test four or five of these items, but you may need
to buy separate kits for chlorine/chloramines and dissolved oxygen. Pet or
garden-pond stores have these kits, or you can purchase them from an online
vendor (searching under outdoor pond test kits will yield good results).
The kits are easy to use and take
only a few moments to give you readings. For a new pond, test the water twice a
week until the values stabilize (about six weeks). After that initial period,
test your pond water once a week.
Remember
Be consistent by testing at the same time each day. Water chemistry values change as the day progresses, so testing your ammonia values, for instance, at the same time each day gives you a more accurate comparison. (Most koi owners test their water around 4 p.m., just before they feed their koi.)
Log your water-testing readings,
noting the day and time for each one. The numbers or values help you track your
pond’s chemistry
The following sections explain
the values you need to track.
Ammonia
Your goal on ammonia levels is
zero, but your readings may change depending on the time of day you take them.
The ammonia levels rise a couple of hours after you feed your fish as the fish
process their food and excrete the leftovers into the water. As the pH
naturally rises through the course of a day, the ammonia is temporarily converted
to ammonium as each ammonia molecule takes on an additional hydrogen atom
(conversely, when pH falls, the extra hydrogen atom is plucked off the
ammonium, converting it back to ammonia). This cycle explains why you want to
test for ammonia at the same time of day (or go crazy trying to figure out what
those ammonia levels really mean).
You can lower high ammonia levels
by dilution, in other words a partial water change, which we describe in the
section “When You Need to Change the Water,” later in this chapter.
But when the readings are
consistently too high, you need to figure out the reason.
- Is your pond new? New pond syndrome, as it’s called, is characterized by changing water chemistry readings that are too high or too low. This problem may take six weeks to stabilize. This is a natural process, and, if your pond was set up properly, should pass without incident. Do monitor your koi for signs of stress, however, and perform a partial water change (see “When You Need to Change the Water,” later in this chapter) if they appear to be in trouble.
- Is your pump doing the job you thought it would, or do you have too many fish for your biofilter? Ammonia values can spike even if you’ve had your pond in operation for years. (Those little rascals grew, didn’t they, and how can you get rid of fish that know your voice and respond to their name?)
To check the gallons-per-hour of your pump, attach a flow meter (available at an outdoor pond supply store) to the output and check it after 15 minutes. By multiplying the 15-minute reading by 8, you can determine if the pump is pumping enough water to circulate the water in your pond every two hours.
Depending on your biofilter media
(see Chapter Planning
Your Koi Pond for info on this essential piece of equipment), you may be able
to switch to a newer high-surface-area biomedia that increases the surface area
of your biofilter. As a basic figure, plan on 24 square feet of biofilter surface
for every pound of koi (the average 12-inch koi weighs 0.7 pound, or about 11
ounces), so the 24-square-foot surface accommodates approximately one 12-inch koi,
with a small safety margin.
pH
The perfect pH range for a koi
pond is 6.8 to 7.2, but koi can do quite well with a broader range, from 6.5 to
9.0. When your pH reaches the lower end of that range, however, you need to
worry about your biofilter as well as your koi. The friendly bacteria in a
biofilter quit working if the pH goes below 6.0. As the bacteria begin to die
off, their vital role in converting ammonia to less toxic nitrites and nitrates
will cease. Ammonia levels will skyrocket, often very quickly, and your fish
will become stressed and may die.
Remember
Don’t take any single pH reading to heart. Your pond is a dynamic system, and its pH changes during the passage of a day, with lower values in the morning and higher ones in the afternoon. A heavy rain can nudge your pond toward a lower, acidic pH, and some pond additives push the numbers toward the higher alkaline side. If the fish look fine and other chemistry values are okay, relax. Koi are adaptive as long as the pH changes aren’t sudden or extreme.
Warning!
Your biological filter and weekly water changes help narrow the range of your pond’s pH values, but don’t be surprised if you get a lot of uninvited advice about pH. Well-intended people will insist (in gentle, soft voices) that adding baking soda is an easy, safe way to lower the pH. Keep in mind (and whisper it gently back to these nice folks if you want) that pH, ammonia, and nitrite are all interconnected. Using a sledgehammer like baking soda on pH is a good way to throw your water chemistry values seriously and immediately out of whack. You don’t need to manipulate your pond chemistry values that badly. Skip the baking soda.
Nitrites
Like ammonia, nitrites are byproducts of digestion, and you want them to be as low as you can get them. The best nitrite level to shoot for is zero, but this may take a while if you’re working with a new pond that hasn’t settled down. (The cyclical chemistry of new ponds includes rising nitrite levels as ammonia levels decrease.)
Tip
Trying to figure out this chemistry balance can be confusing to a new koi-keeper, especially considering that each pond is unique in this regard; don’t hesitate to call on a more experienced keeper for advice. You should also check your local public aquarium — the staff or volunteers at such institutions are often happy to help serious hobbyists. Test for nitrites at the same time of day, so you have similar readings to compare.
Your filter and its friendly
bacteria generally take care of nitrites, converting them to nitrates, which
are essentially harmless to your koi. You can help lower nitrite levels by
partially changing the water each week or by letting the water from the filter
run through a plant-filled sluice on its way back to the pond. Plants use
nitrites as a food source and will contribute favorably to your water quality.
To make use of plants, arrange
your filter’s outflow to pass through a plastic pond or wide PVC pipe stocked
with aquatic or emergent plants (those that grow with their roots in
water and stems and leaves above it). Water hyacinth and water lettuce are
particularly hardy (if given lots of sun) and amazingly efficient at removing nitrites
and other impurities from the water. Because of their aggressive growth rate,
water hyacinth are not legal in all states, but a wide variety of other plants
will work equally well. Employees at outdoor pond and garden supply shops
should be able to guide you. Please also see Chapter Building
Your Pond for more information on
pond plants.
Dissolved oxygen
The amount of oxygen in your pond
water is important, and although you’d expect it to stay steady, it’s a
dynamic, moving number. Oxygen is used by the friendly bacteria in your filter,
by your fish, and by any decomposing organic material in the pond.
Oxygen is replaced at the surface
of the pond at the water-air interface (the area where air and water
meet). To increase the pond’s absorption of oxygen, simply increase the surface
area of the water. We’re not talking about stretching water, just exposing more
of it to the air. Splashing and bubbling via air pumps and airstones, foam
fractionators, and waterfalls all do the trick.
Adding oxygenation devices to
your pond is a good idea if you have low oxygen readings, but if your readings
are consistently low, you need to figure out the reason. The following are
possible causes:
- Ponds with poor water circulation (due to an awkward pond shape or a water pump that’s too small) usually have a dead space (nonmoving water that sinks to the bottom of the pond). This nonmoving water isn’t exposed to air and can’t pick up oxygen.
- An algal bloom — a sudden explosion in the population level of algae in the pond — can cause a rapid drop in oxygen levels. A number of factors can precipitate a bloom, some of which are related to the particular algae’s biology and a bit complex to go into here. Often such blooms are associated with hot, sunny weather and a spike in nitrite levels from fish waste, the presence of a dead animal, or fertilizer washing into the pond.
An overcrowded pond and hot weather can deplete water of its oxygen. (Fish respire faster in hot weather and, as a result, remove more oxygen from the water.)
- Do you have too many fish for the size of your pond and the size of your pump and filter? (See Chapter Planning Your Koi Pond for a simple calculation of the best ratio.)
- Ponds at high altitudes (Hello, Denver!) are behind the oxygen curve to start with; the oxygen level is lower at high altitudes than at low altitudes. If you live in such an area, be sure to consult with local experts as to the water pump needed for your pond. In all likelihood, you will need one that is stronger than those recommended in Chapter Planning Your Koi Pond.
When You Need to Change the Water
Partial water changes (and adding
a dechlorinator) are a natural part of housekeeping for koi-keepers. The
following are two obvious benefits:
- They’re an easy, inexpensive way to maintain or clean your pond’s water chemistry because they dilute all the bad values that result from koi waste.
- They help moderate your pond’s temperature, cooling the sun-heated pool in the summer and warming the chilled pool in the winter.
Water changes are most important
during the summer when the fish are active and eating heavily. You should do a
20 to 30 percent water change once a week in the summer. You can lessen the
frequency a bit during early spring and fall (every 10–14 days), but once per
week is the best overall policy.
Before you begin the water change, buy a flow meter for your hose so you know how many gallons you’re putting in your pond, rather than guessing. The meter also helps you know the correct amount of dechlor to add and (if your pond is salted) the amount of additional salt you need to bring the readings to the original level. Direct the overflow to your lawn or garden. For ponds with salted water, divert your filter’s outflow into your wastewater system because the salt is harmful to most plants.
Tip
An alternate method to using a flow meter is to mark your outdoor hose spigot at a quarter-turn and time how long it takes to fill a 5-gallon bucket when the spigot is turned to that marking. That way, you can add the hose to your pond, turn the spigot to the marking, and set a timer for a measured water change.
Perhaps the easiest way to effect
a partial water change is to redirect the outflow from your filter so that the
water exits the pond. Another useful method is to use a small submersible pump.
You may already have one on hand to operate a waterfall, or you can purchase
one specifically for water changes. (It’s always good to have one on hand
anyway — if your main pump fails, the submersible can be used to circulate and
oxygenate the water until you replace your main unit.)
To change the water, simply
attach plastic tubing (a variety of widths and lengths are available at pet and
pond stores) to the pump’s outflow port and pump out 20 to 30 percent of the
pond’s water (if possible, direct the water to a garden or somewhere else where
it will be of use). The replacement water should be dechlorinated and about the
same temperature as what’s already in the pond (unless you’re trying to raise
or lower the temperature).
You can also use hand-held
siphons (the water is pumped by rubber ball into a length of plastic tubing) or
siphon the pond water out by filling a hose with water and submerging one end
in the pond. However, these methods require gravity’s help, so you’ll need to
have a low-lying area right next to the pond.
For small ponds or in an
emergency (or if you enjoy the exercise), you can also use a 5-gallon bucket to
remove the appropriate amount of water.
Maintaining a Stable Temperature
Koi do best at 70 to 82 degrees F. However, nothing is ideal. Sudden, unexpected temperature drops can stress your koi. We remember some fall days in Colorado when the temperature dropped from 65 degrees in the morning to 21 degrees in the afternoon. When you get caught by one of these switches, add salt (available in bulk at outdoor pond supply stores) to your pond at
To help you keep your fish comfy
cozy, this section offers ways to deal with colder and warmer conditions.
When the weather gets cold
Koi-keepers who live in the
extreme southern parts of the United States (in the United States Department of
Agriculture zones 9 and 10) don’t need to worry much about pond temperatures.
Cold weather in these areas means less than 60 degrees and it rarely lasts more
than a day or two. Partial water changes (remember to use a dechlorinating
chemical preparation) or a pond cover can keep the pond water warm.
The rest of us, left out in the
cold so to speak, have the choice of covering or heating our ponds or doing
neither.
Covering the pond
If you live in an area with no
snowfall, then building and covering a simple frame around your pond is a
feasible project for the do-it-yourselfer. The process entails building a
wooden or metal framework around your pond and covering the frame with
6-millimeter plastic sheeting, acrylic panels, or even bubble wrap. Be sure to use
rustproof products, such as copper screws or plastic ties or strips, to attach
the cover material to the frame. You need about a foot of space between the
pond and the cover for air exchange. Remember to create an access panel of some
sort (a simple way to do this is to secure one corner of the cover with a
length of plastic tubing that can be easily untied) so you can check the water
temperature. See Figure 9-1 for a sample of this pond cover.
Areas that normally get snowfall
require a pond cover with a bit of a slant to the roof to avoid the weight of
snow buildup. Building a cover like this can be as simple as making two of the
four support legs longer. Koi pond covers are available in knock-down (KD), easy-to-assemble
kits for round ponds up to 30 feet in diameter. See Figure 9-2 for more
details. (The manufacturer says one person can set up a koi pond cover in 30
minutes with no special tools.)
Figure 9-1: A simple pond
cover.
Figure 9-2: A slanted-roof
cover for a koi pond.
Figure 9-3 shows a lower pond
cover with bubble wrap in place. Multiple layers of wrap provide additional
insulation.
Bringing koi indoors
Many pond keepers in the extreme
northern area of the United States with ponds less than 5 feet deep generally
bring their koi indoors during the winter (for the basics of an indoor pond,
see Chapter Keeping
Koi Inside).
Letting a deep pond freeze on top
Other northern koi-keepers with
ponds that are too deep to freeze solid prepare their pond for the winter by
doing the following:
- Prepping their fish, making sure none of them have health problems going into their wintertime slowdown
- Consider turning off the filters (many experts insist the filter be left on; ask your koi friends what they do)
- Adding an ice porthole so gas exchange can take place
An ice porthole is a bottomless
wooden box about 2 feet x 2 feet with a hinged top. You set the box at the edge
of the pond with the bottom edge of the porthole extending a foot down into the
water. A 100-watt light bulb set into the top of the box provides enough warmth
to keep ice from forming inside the box. Air exchange occurs at the water’s
surface inside the box. The electric cord connected to the bulb should, of course,
be rated for outdoor use and can be plugged into the outdoor outlets that power
your filtration system.
Figure 9-3: A simple pond
cover that uses bubble wrap as the cover.
With these basic winterizing
steps, most koi get through the winter and the equally hazardous spring
warm-up.
Heating the pond
Some owners choose to cover and
heat the koi pond over the winter. These owners point out the following
advantages:
- They can interact with their fish all year round.
- Owners have no worries concerning fish that have been weakened by winter’s cold temperatures, fasting, and the resultant metabolic changes.
- The fish stay active, are fed regularly, and can digest the food because they’re warmer.
- The fish grow all year and maintain their weight better than koi who overwinter without heat.
Heated ponds bring sizzling sales
The trend toward heating over the winter is
growing. In Japan, koi were traditionally overwintered in mud ponds, and the
annual pond draining and harvest of the koi was a big event. Beginning in the
1970s, however, breeders found that the growing popularity of the hobby
supported the expense of heated winter quarters for their koi. They had
higher survival numbers, particularly with the yearlings. (The first winter
was considered a great winnower of yearling koi.) In addition, the bigger
fish didn’t falter during the winter, they got even bigger and fatter during
the summer, and they commanded higher prices in October during the
traditional koi sales event. For these big-number breeders, heated ponds pay
off.
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But is heating your pond right
for you? We can’t guess what your heating costs may be (both in setup and in
operating costs) because each pond is different; geographical area, size, and
shape of your pond are all factors. You may want to talk to a couple of koi-keepers
in your area and representatives from firms that build and install pond
heaters, just so you have an idea of the cost of heating your pond.
If you know how many watts the
system requires, you can figure out your electricity costs with these steps:
1. Divide the number of watts by 1,000 to get kilowatts.
2. Multiply the kilowatts by 8,760 (the number of hours in a year) to figure how many kilowatts you’ll use a year.
3. Multiply that product by your utility’s charges for a kilowatt hour to find out the cost of running the heater for a year.
Dealing with hotter temps
As the days heat up during the
summer, check your pond temperature in the afternoon, when the heat is highest.
If the water temperature creeps up to the 80s, you need to act to protect your
koi:
- Make a partial (20 to 30 percent) water change, adding cold water to gradually reduce the pond’s temperature.
- Sling a shade cloth up over your pergola framework to reduce the heating effect of the sun.
- Activate a waterfall feature or pond bubbler. This action will help to increase your water’s dissolved oxygen content (warm water holds less oxygen than does cool water, and also increases the koi’s rate of respiration).
Keeping Predators Away
Oh-oh! You’re missing a koi?
This is fair warning: Other
sentient beings on this earth enjoy koi almost as much as you do. In fact, they
may enjoy koi more than you do. To you the colorful fish are living gems. But
for those other admirers, whether two-footed, four-footed, six-footed, or
no-footed, the koi are a feast in the most literal sense.
The kinds of koi predator you
need to reckon with will depend on two factors: your pond setting and the size
of your fish. Koi-keepers in rural areas or in wooded urban areas find raccoons
and herons to be their major predators. Urbanites add cats to that list and move
herons down to third place.
Larger koi are safer from predation
than smaller koi simply because fewer creatures can tackle them.
Tip
Your predators’ success depends to a large extent on the steepness of the sides of your pond. Ponds with shelves for potted plants provide a ready-made table for nabbing koi because the innocent but curious fish like to come up and see what’s going on. Vertical sides, on the other hand, provide a safeguard against predators; the fish can quickly move deeper into the pond and beyond reach.
When Rover comes over
We have to admit that predation can occur when
you least expect it. We had never thought much about domestic dogs being koi
predators until a koi-keeper told us about her cocker spaniel. The pond was new,
and her dog spent a lot of time looking into the water, evidently fascinated
by the koi that swam at his feet.
The koi may have been equally curious. One day
the owner came out to find her dog standing over a 14-inch koi he had just
lifted from the water. Both dog and koi seemed surprised. The owner put the
koi back in the pond and quickly trained the dog to stay away from the pond.
Moral of the story? If Rover seems curious about
your koi, introduce them to each other so he’ll understand that these are
pets, too. Use whatever method has worked with your dog in other training
situations to accomplish this.
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These are additional suggestions
for keeping your koi safe:
- A fence — even a low fence — around your yard helps deter many predators.
- By keeping brush and other natural cover away from the pool’s edge, you can deter most snakes.
- Vigilance on your part in combination with a free-ranging dog and a bird-netting pond cover can thwart the efforts of predatory wading birds. If the netting droops to the ground, it also prevents most large frogs (bullfrogs are the most serious threat) from gaining pool access.
- Net out turtles and large frogs that move into your pond. Take them to the nearest patch of suitable habitat and release. (Be very careful how you handle large snapping turtles!)
- A number of aquatic insects will prey upon small koi. While dragonfly larvae and water scorpions can take only fry, giant water bugs will attack fish of 4–5 inches in length. All of these insects (especially the giant water bug, fondly referred to in some locales as the “toe biter”) can administer painful bites, so use a net to capture and release them in a local pond.
- Treat snakes with caution (but not fear and loathing) and call a removal service if you don’t feel qualified to remove and relocate them yourself.
Warning!
The one creature that you’re most likely to have recurring problems with is that cuddly-appearing (but ferociously defensive), food-washing, masked marauder of the evening — the raccoon. Raccoons attempt to capture koi of any size and injure those that escape.
Beware the nighttime bandit
Raccoons aren’t just smart, they’re street-smart
as well. They’ve adapted to life in the inner city and in the forested
outskirts. After they locate a food source, they return to it time and again.
Although most raccoons run from dogs and people, some — especially if they’re
very hungry or very well acclimated to people, stand their ground and choose confrontation
over retreat.
Raccoons may carry rabies and distemper.
Persistent raccoons must be trapped and physically relocated miles away or
destroyed. Look in the phone book for a pest exterminator who deals with
wildlife.
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Caring for the Pond through the Four Seasons
Getting a running start on pond
care each season is like entering data into your tax software all year long —
you have a lot less stress when the deadline hits. The following sections walk
you through pond maintenance for each season of the year.
Falling into a slower routine
Your primary goal in autumn is to
remove extraneous organic matter from your pond and filter. Anything organic
decomposes very slowly during the winter, but when spring hits and the water warms,
the bacterial bloom will overwhelm your koi.
Other chores to take care of
before the snow flies include
- Hosing off the filter mats or the bioballs or turning the backwash valve on your bead filter.
- Installing your leaf netting (a net cover to prevent leaves from entering the pond) before the leaves begin to fall and making sure your cover or frame is accessible and ready to install.
- Feeding your koi a high protein diet until the first cold spell, and then switching to the wheat-germ-based diet (see Chapter Koi Nutrition 101 for more on these foods).
- Trimming any plants that dangle into the pond. The cold weather will kill the foliage and the debris will end up in your pond.
- Checking your koi for health problems and correcting them. Their immune system slows down after the pond cools.
- Installing an ice porthole or heater, if either are required.
Settling into winter
After the leaves on local trees
have all fallen, take the leaf cover off. Depending on your setup, you have
different tasks at this point to prepare your pond and koi for the coldest
season. The following points cover each of those arrangements:
- Ponds with heaters: Set the thermostat at 62 degrees. Your fish will eat a bit at this temperature, but not with the eagerness that they show in the summer. Offer food once per day, and carefully monitor the amount they eat and make adjustments as necessary. Please see Chapter Koi Nutrition 101 for more details.
- Unheated ponds: Stop feeding your koi when the water temperature is below 52 degrees. (Their digestive systems are working too slowly to digest the food, and the bacteria in your biofilter can’t keep up with an ammonia/nitrite spike.)
Keep your filter running to deal with fish waste, but turn off the aeration system in the pond because the movement chills the water.
- Uncovered ponds where the access to the pond is through an ice porthole: Check the porthole daily to make certain the light bulb is still on, and replace the bulb before it reaches the allotted hour-life (see the side of the bulb package for this number).
Opening the porthole to check on your chilled koi in midwinter can be a bit traumatic because your koi are lying semicomatose on the bottom of your pond. Some koi are inclined toward one side, and those that are swimming are moving in slow motion. This is normal behavior for very cold koi.
When the temperature hits 60
degrees, you can begin to feed your fish. Use wheat germ–based food (see
Chapter Koi
Nutrition 101) and feed only enough to be consumed in two minutes. (Wheat germ is
easier for koi to digest than the more complex proteins.)
Make a 10 percent water change
every week or two weeks.
Spring into (careful) action
The days are getting longer, the
sky is warmer, spring is right around the corner, and all of your wintertime
worries are over. No, sorry to say. April is the cruelest month, and it isn’t
just because of love. This is the time of year that overwintering koi die.
Their metabolisms have been drastically altered to deal with the low temperatures
and lack of food, and any koi that were not in tip-top shape in the fall are
likely to be in a vulnerable state by spring.
At the end of winter, chilled koi
(and their immune systems) begin to perk up. That’s the good news.
The bad news is that your koi are behind the curve when it comes to waking up. All the bacteria and parasites that have spent the last couple of months slumbering (no, they’re not dead, just resting) in the bottom mulm (the sticky layer of organic material such as unfiltered droppings, odd bits of leaves, and dead plants) of your koi pond are awake and hungry. Like a herd of very tiny Tasmanian devils, they’re
scrounging around for food, and mulm is just the start of what they’ll feed on.
Bacteria will move into any breach in the koi’s skin and immediately start
multiplying, and the external parasites will begin feeding and reproducing.
They’re more awake than your koi’s immune system. Keep an eye out for ailments
such as hole in the side, anchor worms, or fungus. (See Chapter Spotting
and Treating Common Koi Ailments for more on
ulcers and parasites and how to deal with them.) Watch your koi for flashing
behavior, curving the body to scrape along the pond bottom or sides.
Most koi-keepers either feed very
lightly or don’t feed at all until the water edges upward past 60 degrees. Then
the feedings should start small. (We’re not trying to protect your koi’s
delicate digestive systems. Koi are really just fancy digestive tubes, with
just a two-hour delay between feeding and excreting.) The goal is to avoid an
increase in ammonia and nitrite levels while your biofilter bacteria become
active.
As the water temperature creeps
past 70 degrees, you can gradually increase the amount of food, but be stingy!
If your koi take more than a minute and a half to eat, you’re feeding too much.
Feed small amounts twice a day, and test your water for ammonia and nitrite content
at least twice a week. Make partial water changes (5 to 15 percent) weekly to
help keep nitrite and ammonia levels down.
Easing into summer
It’s summertime and the living
is, well, weedy. The increased levels of sunlight may trigger an exuberant hair
algae bloom, a weed that looks like green, slimy cotton candy. (If you run
your fingers through that floating filamentous gunk in your pond, you’ll see
what we mean.) This algae is commonly known as blanket weed. In addition
to being ugly, blanket weed is an oxygen stealer at night.
Discourage blanket weed by
- Shading at least part of your pond; blanket weed grows like crazy in direct sunlight.
- Using a commercial blanket weed killer, one that’s safe for use with koi. These work by removing phosphate and other key nutrients from the water (which blanket weed needs) so the weed starves and shrivels.
- Adding barley straw to your pond. As the straw decomposes, it discourages blanket weed. (Tropical-fish keepers from way back recognize barley as a prime source of infusoria, tiny micro-organisms that are an important food source for many newly hatched fish.)
Tip
You can buy barley straw pads packaged just for this purpose at your local pond or aquarium shop or online. Or, if you need a 50-pound bale, purchase it as stock feed at your local feed store. Because each pond is unique when it comes to blanket weed, you should consult a local retailer or pond owner as to the appropriate amount of straw to use. (We put a chunk of the bale into a nylon mesh bag used for laundering delicate washables, add a rock for ballast, and hang the bag in our pond.) Replace the barley straw pad every three months during warm weather.
You can also buy barley straw
extract from some outdoor pond stores, or via the Internet, and not have to
wait a couple of days before the blanket weed diminishes. Your retailer can guide
you as to the appropriate use of this product in your particular situation.
- Using an electronic device that disperses a mineral that kills blanket weed. Note: The manufacturer apologetically explains that the device is not suitable for use with invertebrates or mollusks, so kiss goodbye, metaphorically, any dragonfly larvae or snails you may have in your koi pond (Where have they been hiding? Koi love snails, and not platonically.).
As temperatures rise, the
oxygen-carrying capacity of water drops. On hot days more koi are near the
surface of the water. The koi that are gasping at the surface are seeking air.
Add aeration via water bubblers, fountains, or a waterfall. The increased aeration
these provide allows the fish to obtain more oxygen. A partial water change of
20 to 30 percent can also help by temporarily lowering the water’s temperature
(please see Chapter Maintaining
Your Pond for more details).
Summertime is the best time to
bring out your high-protein koi foods. Your koi are hungry, having awakened
from their wintertime rest during the spring months, and they want food,
glorious food.
Remember
With these rapacious appetites comes a big increase in ammonia and fish poop production, so clean your mechanical and biological filters weekly.
When you’re shopping around, keep an eye out for end-of-the-season bargains. For example, filter material goes on sale in late summer. You can stock up and save a bundle (which you’ll immediately spend on koi, because this is when they come out of the mud ponds in Japan). The downside, of course, is finding a place to put the items until you need them. But isn’t that why car trunks and deck-side storage benches were invented?
by R.D.Bartlett and Patricia Bartlett
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