How Do I Prepare My Pond For Winter?

How do I prepare my pond for winter? That is a very good question. Because during this period of the year, the temperature differences between day and night can be huge.

The water temperature also drops and the activity of the filter decreases slowly but surely.

And proper maintenance in the autumn ensures that the pond will not suffer from poor plant growth or growth of algae next spring.

In this article, I will explain how to prepare a pond for winter.

1. When Should I Prepare my Pond for Winter?

Getting your pond winter-ready usually starts in autumn. When temperatures start to drop, leaves fall from the trees and all living creatures start preparing themselves for winter. It is important to take action around this time of year and make the necessary preparations.

By taking the necessary preparations in autumn a pond will not suffer from algae growth when spring comes around the corner. Also, plants will grow back healthier in spring.

But because winter arrives at different times in the world it could be that the maintenance for autumn is earlier or later than the usual Oktober and November months. Australie for example winter starts when Europe has summer. In big countries like Canada or the U.S.A seasons can vary as well.

The best way to figure out when to start necessary preparations in autumn is by keeping an eye on the water temperature. As soon as the water temperature drops to a steady 50 degrees Fahrenheit (10 degrees Celsius). You are ready to start preparations.

And not only for plants and algae but also to protect the fish. Because the colder it gets the less active fish will become and some even will lie still on the bottom. The water is slightly warmer at the bottom than at the surface. Why fish go to the bottom.

And when a pond is prepared too late in the winter season the fish will be disturbed in the coldest months. Which could cause the fish to come out of their hibernation state. Meaning that the fish could not survive the winter.

Why it is so important to take the necessary preparations on time to ensure a healthy pond and healthy fish when spring comes. Let’s go to step 2 of how do I prepare my pond for winter?

How Do I Prepare My Pond For Winter? - Autumn
Start of Autumn

2. How to Prepare the Surface of a Pond

During autumn, plants and trees will lose their color, and soon after leaves will fall down, straight into your pond. And when these leaves remain in the water they will start to rot. Which will pollute the water. But not just leaves also twigs and dead insects could be in the water.

Keep cleaning daily or as often as you can until there are no more leaves falling from the trees. A landing net to remove newly blown-in leaves and dirt every day is a great tool to use.

While cleaning the surface from leaves it is also a great time to prune overgrown plants and reed. But do not remove too much during pruning. Fish need hiding places from predators. Try not to cut back more than a 1/3 from the healthy green parts.

If you have lilies it is best to give them some extra attention. A lot of plants can withstand winter and are present again when spring arrives. But lilies are sensitive when it comes to frost. After pruning lilies, make sure they are at least 20 inches (51 centimeters) deep and there is no possibility that frost can reach them.

In doubt move the lilies indoors and store them in stand pots in shallow water so the roots remain wet.

Tropical plants are like tender houseplants. The best is to move them indoors and like lilies put them in stand pots in shallow water so the roots remain wet. Let’s go to step 3 of how do I prepare my pond for winter?

Water Lilies
Water Lilies

3. How to Prepare the Bottom of a Pond

Just like the surface the bottom also needs cleaning from leaves, twigs, and other forms of dirt. But mainly from accumulated soil sludge. Which is a great source for bad bacteria to grow. And that can seriously affect the water quality, especially in spring. And the bottom seriously needs cleaning before winter kicks in.

If there is no way to remove sludge and dirt with a scoop net in between the plants. A pond winterization kit can do wonders like Microbe-Lift or API. Which are bacteria to counteract the sludge. While maintaining the health of the fish of course.

Without plants on the bottom, it will be a lot easier to remove sludge. And a handy tool you can use for that is a pond vacuum to clean the bottom thoroughly.

But whatever you do, there is no need to change the water or exchange it completely with fresh tap water. It is a common misunderstanding actually. As a matter of fact, the water in the pond is not dead or old it is filled with beneficial bacteria. Which will help to keep the ecosystem in balance.

However, 25-30% water changes to maintain the balance can be a good thing at times. Also with evaporation, it is a good thing to add some water. But when tap water is being used always use a dechlorinator. Tap water contains chlorine and chloramine which is very toxic for fish and plants. Whenever possible try to keep the ecosystem in balance. Let’s go to step 4 of how do I prepare my pond for winter?

How Do I Prepare My Pond For Winter? - Leaves
Autumn Leaves in a Pond

4. Preparing the Filter Before Winter

A lot of people use the winter period as an opportunity to clean the filters thoroughly and store the filters away until spring. This however is very unwise.

Filter material contains beneficial bacteria that keep the ecosystem in balance. And cleaning a filter will only destroy the colonies of beneficial bacteria.

This means you have to start all over again in spring by creating a balanced ecosystem and that can take months to restore.

The only time it is wise to clean a filter is when sludge is present. Sludge usually sits at the bottom of a filter. And removing sludge reduces the risk of germs and infections in the pond.

However, the filter mats or filter sponges should remain completely intact. Rinsing filter mats or filter sponges with a little lukewarm water is sufficient enough.

The most important thing is to keep filters and pipes from freezing. Insulate the filter with bubble wrap or add an immersion heater and set it at 40 degrees Fahrenheit (5 degrees Celsius).

So the heater turns on when temperatures are below 40 degrees Fahrenheit (5 degrees Celsius). Another way to prevent filters from freezing is by placing them deep enough.

If there is no way to prevent filters from freezing, then by all means remove them from the pond. Especially with a shallow pond (less than 20 inches or 50 centimeters) or in a region where winters are harsher than other regions. Let’s go to step 5 of how do I prepare my pond for winter?

How Do I Prepare My Pond For Winter? - Filter
Harsh Winter Area

5. Preparing the Pump Before Winter

Just like the pond filter, it is advisable for the pond pump to stay in the pond during the coldest months of the year. Unless the pond is shallow or you are 100% sure the pump will freeze. Definitely remove the pump. Otherwise, just leave it. But before actually leaving the pump alone.

The pump in the pond needs some attention before winter kicks in. Rinse the pump thoroughly with water and place it back in the water about 12 inches or 30 centimeters below the water surface. The pump ensures that the water keeps flowing but let the pump run at half speed. That way the flow will not disturb the fish.

With a shallow pond (less than 20 inches or 50 centimeters) it is better to remove the pump from the pond during the coldest months of the year. Or else the pump can freeze. Therefore, remove everything that can freeze hoses, pipes, anything.

After everything pump-related is out of the pond clean it thoroughly with water and store the pump in a frost-free area. But do not just put it somewhere dry or else the rubbers might dry out. Store the pump in a bucket or container of water. Let’s go to step 6 of how do I prepare my pond for winter?

Freezing Pond
Freezing Pond

6. Testing the Water Quality

The smell of fresh autumn rain is for me a great sense of feeling but rain and snowfall affect the quality of the water. The hardness (GH) of the pond water always decreases slightly, but in autumn and winter, this deteriorates even more. Because rain and snow cause acidification.

By keeping the water values ​​up to standard, you will allow oxygen plants to get through the winter well and to ensure that they sprout immediately in the spring and therefore contribute directly to the supply of oxygen in your pond. If this does not happen, the pond will then suffer from algae growth.

Water tests are essential for a healthy pond. Not just for the fish but also for the plants. The Pond Master Test Kit from API tests the most important levels in the pond fast and accurately. Let’s go to step 7 of how do I prepare my pond for winter?

7. Adjusting the Water Parameters

If all water values are in order then awesome. But if the water values are not in order then this will be a great time to correct them.

Optimal Water Parameters are.

How Do I Prepare My Pond In Winter Water Values
  • pH; When pH levels are off API pH up and pH down is great for fixing those levels. Without harming any fish. Read the instructions on the bottle on how to use it.
  • GH; GH levels are fixable with Velda GH Plus. Read the instructions on the bottle on how to use it.
  • KH; With KH levels I recommend Velda KH Plus. Read the instructions on the bottle on how to use it.
  • Phosphate; The Pond Phosphate Remover from Microbe-Lift removes phosphate from pond water safely. Read the instructions on the bottle on how to use it.
  • Ammonia; In order to change the ammonia levels a daily partial water change of 25-35% will help. Test the water quality daily and always use a dechlorinator with the use of tap water. An ammonia remover is also very effective in removing ammonia.
  • Nitrite; With nitrite change the water daily partially about 10-15%. Test the water quality daily and always use a dechlorinator with the use of tap water.
  • Nitrate; Nitrates are adjustable by doing partial water changes of 50% a few times a week. Test the water quality often and make sure the freshly added water is around the same temperature as the water in the pond. And always use a dechlorinator with the use of tap water.

Let’s go to step 8 of how do I prepare my pond for winter?

8. The Battle Against Filamentous Algae

If the water quality is in balance and the pond is still full of filamentous algae you can try Microbe-Lift/AlgAway 5.4 which will help in stopping algae growth.

In autumn filamentous algae will keep growing, unlike regular water plants. And because of that, a pond can still suffer from filamentous algae in late autumn.

By addressing filamentous algae before winter kicks in. The chance of explosive growth of filamentous algae in the spring is also much lower. Let’s go to step 9 of how do I prepare my pond for winter?

Beautiful Pond
Beautiful Pond

9. Should I Turn the UV Lamp Off

The growth of algae will decrease in the winter period because the sun is less powerful and does not shine as much. The water temperature will go lower and lower and once the water reaches a temperature of 50 degrees Fahrenheit (10 degrees Celsius) or lower. Algae will generally no longer grow or have a chance to develop.

Which is a good thing because the UV lamp is mainly for killing filamentous algae and the UV lamp has no effect in winter. Why you can turn the UV lamp off.

If there is no pond heating system and insulation is not much present as well. I recommend not only turning off the UV lamp but also disconnect it from the filter system. Store it indoors until winter is over.

But if there is an overstocking of fish and the UV lamp also has to function as a sterilizer, by all means, keep it on during winter. Let’s go to step 10 of how do I prepare my pond for winter?

How Do I Prepare My Pond For Winter? - Winter Sun
Winter Sun

10. How to Protect a Pond Against Herons in Winter

In areas where it is freezing and winters are harsh predators most likely will not be an issue as they are in hibernation or migrated. Fall, however, is the season you want to watch out for when wild animals are fattening up for the winter. Also, I am not familiar with all the predators from every continent so I will stick with the ones in my area which is The Netherlands, and over here herons can be really annoying.

For herons, it is difficult to find food during the autumn which makes a pond a great buffet. There are several ways to keep predators out of the pond.

  • Place motion detectors with alarms, this will not only scare herons but also cats and other animals.
  • Pond protector electric fences can help out a lot as well with keeping herons away.
  • A landing net does not only keeps leaves out of the water but also protects against predators.

Let’s go to step 11 of how do I prepare my pond for winter?

How Do I Prepare My Pond For Winter? - Heron

11. Should I Feed Fish During Winter

In the winter months, the fish go into a kind of hibernation. This ensures that they have to use as little energy as possible in these harsh times. And because of that fish will eat less.

When temperatures in the water are dropping fish will no longer be able to digest normal food properly. This is because the metabolism of fish works slower when water temperatures are lower. Why it is better to switch to a more easily digestible food in the fall.

And when water temperatures are at a consistent 50 degrees Fahrenheit (10 degrees Celsius) there is no need for feeding at all. If fish are being fed the same as in summer they simply will not eat it. Food will then fall to the bottom which will rot and mess up the balance in the water. Always use an original thermometer for ponds with a test for water temperatures.

Before winter kicks in it is a great idea to treat fish for bacteria, infections, and parasites. Winter is a harsh time for any outdoor animal so make sure the fish are healthy. Let’s go to step 12 of how do I prepare my pond for winter?

Goldfish in a Pond
Goldfish in a Pond

12. Should a Pond Stay Open in Winter

It depends, there are two options to choose from. Build a greenhouse or close the pond partially.

12.1. The first option is closing the pond partially.

Because when a pond starts to freeze fish will survive as long they have 18 inches (46 centimeters) of water. So there is no need to panic when it starts to freeze outside. Fish will not be in danger right away. Fish will be in danger if it is freezing for more than a week because toxic gas under the ice can build up.

So yes it is important to keep the pond open. But a hole is sufficient enough to provide enough oxygen. There are several options to keep a pond open or re-open.

A good quality de-icer with at least 1200 watts will ensure that the hole remains open throughout the winter, giving your fish the healthy environment they need.

Should a Pond Stay Open in Winter
A Pond With a Big Hole

But do not chop a hole, but instead, put a pan with hot water on the ice to melt a hole in the ice. This way you will not scare the fish to death. And a powerful air pump with an air stone will also do wonders.

When it comes to snow it is better to remove it because snow prevents sunlight from entering the pond. Fish and aquatic plants like sunlight and it is good for the climate in the pond.

Waterfalls can help in keeping a pond open as well. They can help with providing aeration. But if you decide to turn the waterfall off then make sure it is winter-ready. Drain all pipes and tubes, turn off UV lights and filters and store them away indoors until spring comes back.

12.2. The second option is building a greenhouse.

Building a greenhouse is a great way from protecting a pond from freezing, especially for smaller ponds. With a greenhouse, fish are also protected against predators but there has to be ventilation for gases to be able to escape and for fresh air to come in.

A greenhouse is easy to build too lumber or pipes will work well for this and for insulation bubble wrap is awesome.


Thank you for reading my article about how do I prepare my pond for winter?

Preparing a pond before winter can be a tough job but very rewarding when spring arrives and everything blooms, the water is clear, the fish are happy. Because the basis for a beautiful pond in spring is done in autumn.

And if there are any questions on how do I prepare my pond for winter? then I would love to see them in the comment box below. For more information about ponds click here.


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