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? Larger ponds have the benefit of stabilizing thermal and chemical changes. These slower temperature swings will benefit fish health. Locating the pond in a full sun location is the recommendation of many horticulturists because waterlilies grow and bloom better in full sun. 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. Raising the pond a few inches to a couple of feet will also keep runoff from washing in chemicals and organic matter. These are just some of the design considerations that must be factored when developing a site plan for ponds. The following article will outline the changing maintenance requirements of the pond throughout the annual cycle.

WATER TEMPERATURE 70 TO 50 DEGREES

As the water temperature drops, the pond and fish are prepared for winter dormancy.

Water Quality: Tests should be done for ammonia, nitrite, nitrate, pH and salt levels. Test the water used for filling the pond before each filling. The level of nitrites acceptable for human use can be deadly to fish.

Inexpensive disposable netting as well as high quality reusable netting materials prevent the buildup of leaves. If the plan is to cover the pond every fall, consider a more expensive reusable net that uses stakes, grommets, and poles.

Fish: 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.

WATER TEMPERATURE BELOW 50 DEGREES

The pond is going into dormancy.

Water: The best possible time to do the clean-out, from the fish's viewpoint, is when the pond water temperature is the same as the hose water. Simply remove the fish, putting them in tubs of pond water and place a net over the tub. 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.

Fish: As the fish go dormant they move more slowly 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 them.

Plants: Stop fertilizing plants several weeks before the weather changes in the fall. That way the plants can consume the fertilizer without leaving a lot of nutrients for algae after they go dormant.

After the frost has killed the tops of perennials, cut the leaves back just above the level of the pots. 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.

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.

Water: If the pond is capped with ice, 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 cost less to run than de-icers, but may not work when the air temperature drops below the teens for extended periods of time. Thermostatically controlled pond de-icers keep a small area free from ice cover as temperatures drop into the single digits.

As the water warms up, the fish may begin gasping for air at the surface; this can indicate either low oxygen levels 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. If necessary use hot water pots to melt a larger hole.

Plants, 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. This is the time of year to order replacement filter mats, bacteria, replacement ultra-violet light bulbs and any other replacement parts you will need to start the system when the weather warms up.

WATER TEMPERATURE BELOW 50 DEGREES

The pond is coming out of dormancy.

Fish: Some microscopic parasites are active in water in the forties; others wait until the water is in the fifties. These pests are most active when the fish's immune system is at its weakest. Fish weakened by low oxygen levels or from excessively cold water are the first to become infested with parasites. These conditions along with a poor diet in the fall and poor water quality also make the fish much more prone to bacterial infections in the spring as the water warms up.

Plants, Pumps, and Filters: Plants that were moved down to the bottom of the pond can be moved back up to sunny shelves. They will sprout faster as the sun warms the soil. Be careful not to let them freeze during a late season cold spell. Marsh marigold and skunk cabbage are two native shoreline plants that will bloom in these colder temperatures, but most plants will just be sprouting a few leaves.

In the spring the pump and mechanical filter or skimmer can be started when the water rises into the upper forties. Do not use bottom drains or circulate water from the pond bottom when the water will be chilled by colder air. Biological filters should be started when the water reaches the mid-fifties.

Follow the manufacturer or supplier's recommendation on changing the oil in oil-cooled pumps. Check the electrical cords, connections and outlets. Be sure to use ground fault circuit breaker protected outlets on all electrical equipment that come in contact with the pond. Prolonged exposure to electrical current can kill or disfigure the spines in fish.

WATER TEMPERATURE 50 TO 70 DEGREES

As the water temperature rises it is time to prepare the pond and fish for an active growth cycle.

Water Quality: Lower the water level so that a maximum of thirty percent is changed. Be sure to do the cleaning and then fill the pond to neutralize chlorine and ammonia. For optimal fish care, tests should be done for ammonia, nitrite, nitrate, pH, alkalinity and salt levels. The level of nitrites in tap water acceptable for human use can be deadly to fish, but you won't know that until the fish are in bad shape, so test first.

Plants, Pumps, and Filters: Submergent plants may be added to the pond when the water temperature reaches the mid-fifties.

Hardy shoreline plants and water lilies can be added when the water is in the sixties. Begin fertilizing plants at this time. Divide and repot plants when they are just starting to leaf out.

Algae is one of the biggest problems pond maintenance companies face. Bacteria and plants compete with it for nutrients and floating plants and lily leaves compete with it for sunshine. A good pond and filter design will prevent green water and limit long string algae growth. High levels of green water algae can cause oxygen problems in the pond.

Even though plants release oxygen during photosynthesis, they also consume oxygen all the time through respiration. At night they release carbon dioxide that becomes carbonic acid. The acid lowers the pH at night causing fish health problems in addition to low oxygen levels. The fewer nutrients that are added to the water, (fish food and debris like falling leaves) and the more consumers of nutrients there are, (bacteria and plants) the better the pond balance will be.

WATER TEMPERATURE ABOVE 70 DEGREES

This is the best time to enjoy the pond, when it looks its nicest and attracts the most songbirds.

Water Quality: If the water becomes very warm (over eighty-five degrees) be careful to watch the fish for any signs of unusual behavior. If they are gulping for air at the surface or near the waterfall, the water is low in oxygen. You can observe significant trends by recording readings from weekly tests in a journal.

Fish: Feed fish a balanced diet with a variety of fresh and pelleted foods. Fish left to fend for themselves do not grow as much and may not put on enough fat stores to go into the next dormant season in a healthy condition. On the other hand, healthy fish can grow rapidly and may grow too large for the existing pond. The addition of large numbers of babies may outgrow the filter system as well. Remember, fish grow and filters don't. It may become necessary to remove some of the fish to keep the pond in balance.

Plants, Pumps, and Filters: Tropical plants can be added when the water is in the seventies. Lotus should also be added, even though it can survive being at the bottom of a frozen pond. When plants begin their blooming cycle be diligent about removing dead leaves and spent flowers. Flower removal will promote more blooming in many species of plants.

Large koi can damage plants by their constant nibbling on the leaves and soil. Large gravel should be used to cover the soil in pots and be placed around the base of plants that are planted directly into the gravel.

Bacteria may not need to be added to the filters the rest of the summer. It should be growing on the surfaces of rocks in the pond as well. If the filter material is cleaned off, especially by chlorinated water, or by drying, new bacteria should be added.

By following these simple suggestions you should be able to maintain a thriving aquatic environment for plants and tropical fish throughout the year. LASN