Good filtration and occasional maintenance keeps a pond attractive all season long.

An external skimmer box is hidden in the ground outside the pond, usually closet to the house for the shortest electrical run and for aesthetics-so the box opening into the pond is hidden from the viewer. In addition, the lid has the appearance of a stepping stone so it blends into the landscape surrounding the pond.

Unskimmed ponds will collect seeds and debris as shown here. A pond covering such as fine mesh netting is a useful tool that helps keep leaves and debris out of the pond during Fall.

Waterfalls can be kept running for winter beauty. If keeping fish, however, it's best to shut off the waterfall pump when temperatures drop below about 25 F, so the water is not artificially chilled.

This biofilter/waterfall keeps the pond water clear and safe for fish in the summer. It is cleaned about once a year (usaully fall) depending on the number and type of plants in the pond, fish load and size of the pond.

In zone 5 and colder climates a small pond pump placed near the surface will keep a hole open in the ice. A 1000 watt heater is recommended, however, if temperatures drop below about 5 degrees F.

If your pond freezes over with fish living in it, don't break the ice with heavy blows that could harm the fish. Instead, use a pot of hot water placed on the ice to melt a hole(center), so the fish can breath.

If your pond is not over crowded and is free of decaying debris, the fish can live under the ice for a day or more without air, though typically you want to insure the hibernating fish have a continuous opening on the far side of the pond so they receive proper aeration.

During the season a pond skimmer and biological filter cuts pond maintenance to about 5-10 minutes a week.

Before the pond is built there are design and construction decisions that influence the amount of maintenance that a pond will require. Is the pond going to be a small water garden with few fish and plants or will it have a large body of water with planted edges? Another possibility is the koi pond designed for raising three-foot long colorful fish from Japan. Larger ponds have more water obviously, but the extra depth and width have the benefit of stabilizing thermal and chemical changes. Slower temperature swings will benefit fish health. Lower, diluted nutrient levels will allow plants and bacteria to keep ahead of algae.

A buffer zone around the pond's edge made of perennials and shrubs will keep chemicals used in lawn maintenance from drifting in during application or washing in during runoff. Raising the pond a few inches to a couple of feet will keep runoff from washing in chemicals and organic matter. In some designs a higher edge around a pond will help keep out leaves and provides the opportunity to have a seat wall that gives closer access to the water for some people.

Locating the pond in a full sun location is the recommendation of many plant people because many waterlilies and other plants grow and bloom better in full sun. On the other hand, water gardens often look better with overhanging branches from trees and shrubs. Tall background plants help frame the pond, screen out unwanted views and provide nice reflections. With the possibility of lots of leaves falling into the pond, the filter system design plays an important role in the amount of maintenance the pond will require. Automatic pond skimmers (not the swimming pool type) that pull leaves and other debris into net bags are a huge help when the alternative is to net the sunken leaves off the pond bottom by hand. The traditional method of putting the pump in the pond creates high maintenance for the pump and filters. Leaves plug the pump and ground up leaves plug or degrade the filter. Putting the pump in a skimmer where it is protected by a net and filter mats simplifies maintenance year round.

No matter what design style or construction materials are used, the biological ecosystem of a pond or water garden is essentially cold blooded. The life cycle of every organism from the bacteria to the largest cypress tree depends on the temperature of the air and water. All of the routine maintenance chores pertaining to the plants, fish, other animals, filters, and the water itself are best done at the proper time. This timing is not done on a calendar basis, but rather is done on a thermometer basis.

A thermometer, water test kits and a record keeping form are all very important tools to use in maintaining the health of a pond's plants and animals. The record keeping form may be the most important tool of all. To solve a problem after it develops requires the skills of a detective, historian and sometimes a coroner. It helps to have written records of what was recently done to the pond. Even though the designer may not have seen the pond in quite some time, the pond owner will call when a problem develops.

There are four water temperature ranges that are important to the maintenance of a backyard pond. They do not quite correlate with the four seasons. This article will cover the maintenance as the water cools off for winter. The companion article for the water warming up will appear in an upcoming issue of Landscape Architect and Specifier News.

Within each range we will look at jobs to do in the water, fish, other animals, plants, and pumps and filters.

WATER TEMPERATURE 70 TO 50 DEGREES

As the water temperature drops it is time to prepare the pond and fish for winter dormancy.

Water Quality

Water quality is of prime importance, because the fish and plants are living in it. Tests should be done for ammonia, nitrite, nitrate, pH and salt levels. Test the water to be used for filling the pond, before each filling. The level of nitrites acceptable for human use of water can be deadly to fish.

As the temperature begins to fall it is the time to be sure no debris, or decaying organic material will be left in the pond. This organic matter may release toxins, harbors parasites and fills the pond with sludge. The decay of leaves will also consume oxygen in the water, depriving the fish. Winter and spring are both stressful times for the fish and a clean pond in the fall will greatly assist with the maintenance of water quality during these next seasons.

Consider how the pond could be covered with netting if it can't be cleaned on a regular basis. Are there tall plants in the way, including cattails or iris growing in the water? Did the filtration system include mechanical filters like skimmers? Who will be responsible for cleaning them out?

Inexpensive disposable netting as well as high quality reusable netting materials are available for ponds. If the plan is to cover the pond every fall, consider a more expensive reusable net that uses stakes, grommets, and poles. The pond net is like investing in a tent for camping, with proper care it will last for many years.

Leaves will turn the water brown as they decay, just like the organic matter in tea bags turns tea brown. A net that has so many leaves on it that it sags into the water is a giant tea bag. A lot of leaves will turn the water so dark the fish cannot be seen. The tannic acid may also lower the pH of the water. The color does not go away on its own, but it can be diluted through water changes.

Fish

If any of the fish are to be over wintered indoors, they should ideally be moved inside when the temperature is the same in both the outdoor and the indoor pond. Keeping the fish indoors can be quite challenging, as few homes are equipped with the proper sized holding tanks and established biological filtration capabilities. When moving the fish, follow the same acclimating procedures for introducing new fish to the pond.

As water temperature lowers into the upper 60's the fish immune system begins to weaken. It will shut down over the winter. Begin feeding the fish a food lower in protein and higher in carbohydrates.

Other Animals

Frogs and toads may be attracted to ponds as they look for places to hibernate. They will need a pot or tray of soil to burrow into if there is no gravel or rocks to hide under. Many species of insects over winter as larvae or pupas in the water

Plants

Plants will be finishing their blooming cycle. Seedpods will be developing and leaves will begin turning yellow. Remove dying leaves as they fall into the water.

Pumps and filters

At this point, early in the fall there will be little change in the maintenance of the filter system as compared to how it ran over the summer.

WATER TEMPERATURE BELOW 50 DEGREES

The pond is going into dormancy.

Water

Many koi keepers do regular water changes all year long, even in northern climates. Small changes more frequently will be less likely to change the ponds water temperature or chemistry.

During heavy leaf fall periods, daily cleaning of the skimmer may be needed. All of the leaves should be removed prior to the pond icing over. Use a fishing net, swimming pool net, or standard leaf rake to lift the leaves out.

A complete pond clean out may be required. A major pond cleaning is not too difficult or time consuming. If a complete cleaning is going to be done, fall is the best time to do it. The fish immune system is still functioning as compared to spring when it has not yet started up after the winter dormancy. Removing the debris from the pond before it decays and releases toxins into the water is better than waiting until spring. Wait until the leaves are done dropping for the fall to do the clean out. There will be some leaves that will blow in over the winter, but they will require only a small cleaning in the spring.

Simply remove the fish, putting them in tubs of pond water and putting a net over the tub. Begin pumping the water out of the pond. Hose down the pond, and pump or wet-dry vacuum out any debris in the bottom. Be sure there is adequate aeration anytime the fish are stored in temporary, confined quarters. Refill the pond and add chlorine neutralizer to prepare for the fish. Always float the fish in plastic bags to adjust to the new pond temperature before release. The best possible time to do the clean out from the fish's viewpoint would be when the pond water temperature is at the same as the hose water. There well be less shock if they do not have to warm up and then cool down.

Fish

Stop feeding the fish as the water temperature drops below the mid-fifties.

Examine the fish closely when they have been removed for pond cleaning so they can be treated for parasites or disease if necessary and enter into dormancy in peak condition. The fish will have grown in size and perhaps numbers from reproduction and purchases. Now is a good time to lower this number if necessary in preparation for the stressful seasons about to come.

There are far more fish in the average back yard pond compared to the amount of fish in the same amount of water in a natural lake. Small fish require less oxygen than large fish and so small babies survive the winter and the large expensive fish do not. Culling out the number of fish in a pond is a necessary job.

As the fish go dormant they do not move around as quickly and are less aware of predators. The pond should be designed to give the fish protection from predators during this time. Deep areas with vertical walls and rock shelters will help protect the fish.

Other Animals

Frogs and turtles will begin going dormant as the water reaches the low-fifties. Most of the bacteria in the filter system and pond will go dormant as the water temperature drops below the fifties. The biological filter system can be shut down now. If the water is also circulating through a waterfall or fountain they can still be run as long as the water running through the air does not mix with the bottom water.

Plants

Stop fertilizing plants several weeks before the weather changes in the fall. That way they can consume the fertilizer and not have a lot of nutrients left for algae after the plants go dormant.

After the frost has killed the tops of perennials, cut the leaves back to just above the pots. Some plants have attractive seedpods that look nice in winter and can be left for a nice visual effect. Hollow stemmed plants like cattails can be controlled by cutting the stems down below the water level. This section of the plant will die over winter.

Some hardy marginals can be left planted along the shore or potted in pots and they will survive ice around the roots. Others should be moved to deeper water where they will not be frozen solid.

After the leaves of lilies start dying, cut all of the leaves and flower stems off. Move potted lilies to a lower level where they will not freeze solid.

Before tropical shoreline plants receive a frost, they must be moved indoors if they are to be kept alive. Cut back any extra branches and expect some to all of the leaves to fall off as the plant acclimates to the new growing conditions. Put it in the sunniest window possible. Keep a saucer of water filled under the pot so it can remain wet.

Keep the plant in the seventy-degree range and away from dry furnace drafts.

Pumps and filters

In the fall it is best to stop running the pump when the water gets in to the forties. We want to allow the development of the forty-degree puddle that has an insulating layer of cold water above it. Any pipes that may freeze and crack can be blown clean with a leaf blower or shop vac, just do not let anyone look in the other end of the pipe.

The force of water coming out can injure someone.

AIR TEMPERATURE BELOW FREEZING POINT OF WATER

Water

Water is a unique substance. At about 40 degrees F. it is denser than water warmer or colder, so it settles to the bottom of the pond. It forms a puddle that if left undisturbed will not mix with the colder water above it. The ice floating on the top of the pond insulates the lower water from even colder air above it.

Winter pond temperatures can remain very cold for many months in northern climates. There's only so much water in a pond. There can only be so much oxygen in the water. If the ice caps over the pond, the fish and any decaying organic material may eventually consume all the oxygen and the fish will suffocate.

This is referred to as "winter kill" and occurs commonly in natural ponds. It's easy to avoid this by simply keeping a small area of the pond ice-free for the exchange of gases with the atmosphere. Air bubblers and small pumps can be used to keep small areas ice free, but do not allow them to mix the lower 40 degree puddle of water with the colder top layers. They cost less to run than deicers, but do not work when the air temperature drops below the teens for extended periods of time.

Pond deicers are not meant to warm the pond, but just to keep a small area free from ice cover for the exchange of gases with the atmosphere. Keep the heating coil on the deicer clean. Mineral deposits can build up on it, insulate it from the water, and cause the unit to fail. The heating coil can be dipped into lime-a-way or vinegar to dissolve the deposits.

If the fish are gasping for air at the surface, this may indicate either low oxygen or excess toxic gases, like hydrogen sulfide or carbon dioxide. Find a way to enlarge the hole for better gas exchange using another bubbler or heater. Do not pound on the ice. If necessary use hot water pots to melt a larger hole.

Fish

As the water temperature drops through the forties, the fish will become more sluggish and dormant, and begin to live off the fat built up during the warm season. Keeping fish outdoors is safe as long as the pond is managed correctly. Remember, the fish will be dormant in the winter and should not be fed.

Other Animals

Pond inhabitants of northern areas will be dormant, except for some varieties of native fish that will still be taking an ice fisherman's bait. Southern pond keepers will have to keep an eye out for the greatly increased presence of fish eating birds. The egrets, herons, kingfishers, and osprey that inhabit the entire continent during the summer concentrate in the south all winter.

Other animals depend on open areas of water around sunny rocks or from deicers. Birds and mammals may come for a drink or a bath.

Plants

In northern areas all of the plants are dormant. In southern areas, plants may need to be protected from the occasional frost. In very warm areas, plants will still be blooming and green. They may need to be fertilized occasionally.

Pumps and filters

Water features that run during freezing weather can create beautiful ice sculptures. Running the pond waterfalls in winter when temperatures drop below freezing may create ice jams and leaks in the watercourse. These leaks cause the overall pond level to lower, giving the fish less water. Warm pond water mixing with the very cold air could result in excessively cold water temperatures that will harm the fish.

When shutting off the system for the winter, remove the submersible pump, filter mats and any other items from the pond, skimmer and biological filter. They can be cleaned, dried, and stored in a garage or basement until spring. Disconnect the auto-fill valve from the water source to reduce the possibility of freeze damage.

The pump may need additional care beyond cleaning. Refer to the pump's owner's manual for additional information. Some pumps such as the Tsurumi brand need to have their oil changed annually. Other pumps such as the oil less Oase brand, recommend that the pump be stored in a location where it will not freeze, submerged in a bucket of water to keep the seals hydrated. External pumps can be drained and depending on the climate, removed for the winter based upon manufacturer's recommendations. External devices such as ultraviolet lights also have winter care needs, consult their manuals also. lcm

1999 Pond Supplies of America Yorkville, IL (888) 742-5772 Pittsburgh, CA. (888) 772-3278 Los Angeles, CA. (877) 772-7937A