Winterizing Your Water Garden: A Comprehensive Guide

Winterizing Your Water Garden: A Comprehensive Guide

As the crisp air and falling leaves signal the arrival of winter, it is essential for water gardeners to prepare their pond for the colder months. Your water garden needs proper winterization to protect its equipment, plants, and fish. In this guide, we will delve into the steps necessary to winterize a water garden and maintain the well-being of plants and fish.

Clean Out the Sludge

All through the spring and summer tiny plant fragments, dead algae cells, leaves, and other organic matter settle to the bottom of the pond. This decaying material forms a sludge layer that uses up oxygen as it decomposes. This natural clean-up process cannot keep up with the amount of debris accumulation throughout the water gardening season. Fall is the perfect time to remove submerged leaves, twigs, and other debris from the bottom of the pond.

  • Use a leaf or sludge net to remove accumulated organic matter.
  • For larger ponds, a pond vacuum makes the job easier.

It is not necessary to completely drain and scrub the pond at the end of the season. A simple clean-up of debris will do the job.

PRO TIP: You can use a submersible “solids pump” to pump out sludge and debris while making a water change at the same time. Use a pump designed to pump (not filter out) plant fragments and other debris out of the pond.

Aquatic plant care

Aquatic plant care

As the summer season begins to fade away you have probably noticed your pond plants aren’t growing and blooming as much. Leaves have begun to yellow and die. That is because the shorter days and cooler temperatures cause the plants to stop growing. Water lilies, for example, shift their energy away from flowering and towards preparing for dormancy during the colder months.

Trimming aquatic plants

Trim dead or decaying foliage to prevent the accumulation of debris at the bottom of your water garden, which could lead to poor water quality. Discard “annual” floating plants like water lettuce and water hyacinths as they won’t survive the cold weather. There is no need to fertilize plants in the fall, even if you live in a warmer climate where the water does not freeze.

PRO TIP: Some water gardeners move their tropical aquatic plants indoors using an aquarium or kiddie pool. Place the plants near a sunny window or under artificial grow lights. Pond plants require ample light to support their growth. If using artificial lights, provide at least 12-16 hours of light per day.

In cold climates move hardy potted plants to the deepest part of the pond. This prevents freeze damage that can occur in shallow water.

Winterizing the Pump and Filter

Now that leaves, debris, and sludge have been removed it’s time to prepare the pump and filter. Water temperature determines which approach to take. If the water temperature remains above 50°F you should keep the pump and filter running all winter long, especially if you have goldfish or koi.

  • Remove the water pump and clean the intake screen and impeller. An old toothbrush works well.
  • Remove old filter media from the filter. Clean or replace the filter pads. Rinse biomedia with pond water to remove dirt. You can even use a garden hose to blast away sludge if the filter media is really dirty. Despite what you may have been told, tap water won’t hurt the biofilter.
  • Reassemble the pump and filter and make sure it is working properly.

If your pond freezes in the winter, we recommend removing the pump and filter to prevent winter damage. Do this when the water temperature drops to 45-50°F. Clean the pump and filter and store it in a dry place until spring.

Caring For Goldfish and Koi

Caring For Goldfish and Koi

As water temperatures decrease, the metabolic rate of goldfish, koi, and other pond organisms slows down. Fish become less active, which means they’ll swim and feed less frequently. It is important to reduce feeding as the water cools. Your fish don’t need a high-protein diet in cool water. Special reduced-protein fish foods are formulated for cool, fall feeding.

  • Fish eat less when the water temperature is below 60°F
  • Stop feeding when the water temperature is below 40°F
  • Uneaten fish food simply pollutes the water and harms the fish.

The Importance of Oxygen

Even if your pond freezes, fish and other aquatic life like snails and frogs need oxygen during hibernation. Oxygen finds its way into the pond through a dual process: it diffuses from the air to the water through wind across the water surface, and it's also generated within the pond by algae through photosynthesis. Ice on the pond's surface prevents oxygen from diffusing into the water. The only source of oxygen is from algae living in the water and growing on the surface of the pond liner.

If the ice layer is thin and transparent, sunlight can pass through and stimulate algae to produce oxygen. However, if the ice becomes thicker or snow-covered, the oxygen level starts diminishing. This is due to the lack of light reaching the algae and continual consumption of oxygen by pond organisms and decaying organic matter during the chilly winter months. This can lead to “Winterkill” where fish and other aquatic animals die from lack of oxygen.

Consider a Pond De-icer

The easiest way to prevent winterkill is with a pond de-icer . A common misconception is that de-icers, also called pond heaters, warm up the entire pond. This is unnecessary and would be very expensive to achieve. A de-icer uses very little energy and protects the fish from Winterkill.

A de-icer floats on the water surface and prevents the water around the heater from freezing solid. This allows oxygen to enter the water and prevents excess carbon dioxide and harmful hydrogen sulfide (rotten egg gas) from building up under the ice. If the pond water freezes solid with no gas exchange, your fish could be stressed or even die from poor water quality. If your pond water never freezes, a de-icer is unnecessary.

Maintaining Water Quality

A well-maintained pond normally has good water quality. But that doesn’t mean you don’t need to test the water. Testing the water only to find out everything is OK is like getting a good report from the dentist. It’s good news! It also allows you to detect and correct water quality issues before they become a serious problem. Pond test kits are inexpensive and easy to use. Here are the main parameters to check.

  • pH naturally rises during the day and drops at night. pH in the morning hours should be between 6.8 and 8.5. The important thing is to avoid pH levels that are consistently below 6.5 (acidic).
  • Ammonia and nitrite levels should always be zero. A positive test result is usually due to overfeeding or too many fish in the pond.

If you live in a mild climate and feed your fish all winter, test the water once a month to track water quality. If your pond freezes, test the water after you’ve performed the initial debris removal. If any of the water quality parameters are out of range, make a partial water change (25%) and re-test.

Keeping Tree Leaves Out of the Pond

If your water garden is near trees, chances are tree leaves will blow into the water in the fall. Many water gardeners stretch leaf netting across the surface of the pond to prevent leaves and other debris from settling into the water. Pond netting is nearly invisible and allows sunlight to penetrate the water. Never cover the pond with a plastic tarp as it will block sunlight and inhibit the algae’s ability to produce oxygen.

Final Thoughts

Winterizing a water garden is not difficult and is an essential part of caring for your equipment, plants, and fish. By following these steps and tailoring your approach to your specific water garden's needs, you can ensure the survival and well-being of your aquatic plants and fish through the winter months. With proper care, your water garden will emerge from hibernation, ready to flourish once again as spring arrives.

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