Water gardens add a special effect to the landscape and fish are easy-to-care-for pets. A properly functioning water garden takes care of itself naturally throughout the growing season. Submerged plants and scavengers help keep algae populations from getting out of hand.
As winter is upon us, though, water gardens do require some special care for their survival.
Remove fallen leaves and twigs from the pond to prevent injury to the fish. Prevention is also easier than having to clean the entire pool in the fall by using netting stretched across the pool to catch leaves or by using a skimmer to remove leaves on a regular basis.
If you have fish, feed them extra food as the temperatures cool and continue until the water temperature drops below 45 F. This allows the fish to build up additional fat stores for winter survival. Fish don't need to be fed during the winter because their metabolism virtually shuts down in water temperatures below 50 F. However, feeding is OK during warm conditions.
Most fish can be left in the pool year-round as long as ice doesn't cover the entire surface for more than a week or two. If the fish are to remain in the pond throughout the winter, it is necessary to keep an area free of ice throughout the winter to allows the exchange of gases such as carbon dioxide, methane and hydrogen sulfide that result decaying organic matter. The buildup of these gases is toxic to fish. A 1-foot diameter opening per 100 square feet of pond surface area is adequate.
As their foliage begins to turn brown, reduce the marginal aquatic plants by two-thirds of their height to prevent debris accumulation and breeding grounds for pests. Do not prune any new foliage growth that is initiated during the winter, and stop any fertilization practices during the winter months.
Move hardy water lilies and other hardy aquatic container plants to the deepest section of the pond. They should survive as long as the water does not freeze solid to the rootstock. Under the coldest of circumstances, a submergible heater can be installed.
Pumps and filters need to be turned off for the winter, because cold water holds much more oxygen than warm water and the fishes' respiration is slow. The bacteria in your biological filter do not work in cold temperatures.
If you turn off the pump and filter for the winter, be sure to drain all plumbing, as well as external filters, UVs and external pumps. Submersible pumps should be left in the pond or in a bucket of water in a warm place to keep the seals from drying out. In the spring, reinstall the filter, begin feeding the fish and replant if necessary.
Timothy Daly is an agricultural and natural resource agent with the Gwinnett County Extension Service. He can be reached at 678-377-4010 or firstname.lastname@example.org.