Closeup of pond with some leaves floating in itPutting your pond to bed for winter is not a sad process here in the south. Yes, your finned friends will be a little less active for a few months. But our simple koi pond winterization tips will help ensure your fish make it through the cold winter months and see you in the spring.

Please keep in mind that this is only one of a few different times you’ll want to maintain your pond. Knowing how to clean and maintain a pond is essential to keeping it clean, clear, and beautiful.

Read on to find out how to successfully winterize your pond.

The Koi Pond Winterization Process

Install Fish Pond Netting

One of the ways you can help lower maintenance is by putting a net over your water feature before leaves start to fall.

Fish pond netting serves two main purposes: to protect your fish from predators and to keep leaves and other debris out of the pond. In winter, leaves falling into the pond will break down into organic material. This clutters your pond and releases gases that can harm your fish. Installing fish pond netting will help keep your pond clean and your fish safe.

After all the leaves have fallen, you can simply remove the net, throw away the leaves, and store the net away until you need to winterize your pond next year.

Remove Leaves And Debris

a roasting pan with a turkey in it covered in leaves.

If you didn’t install pond netting as part of your koi pond winterization process, you will have some maintenance to keep up with as the leaves come down. Having a long-handled pond net can be very helpful for removing leaves and debris.

You’ll also want to start checking your skimmers more often. More leaves and debris are falling during autumn, meaning your skimmers may fill up faster.

Leaving all of the fall mess can cause multiple problems in your water feature. Some of these can be ammonia build-up, pump clogging, leaks developing, and pond water quality failing. Leaves and debris can decompose in the water and release harmful toxins that can pollute the pond and make your fish sick.

Removing any build-up in the pond or stream is important to ensure a properly functioning water feature.

Trim And Remove Dead Or Dying Foliage

Dying foliage that needs trimming as part of koi pond winterization

Trimming and removing dead or dying foliage from different types of pond plants is important for several reasons. Trimming dead foliage as part of koi pond winterization:

  • Improves the look of your pond
  • Helps keep your fish healthy by removing potential sources of disease
  • Helps remove excessive organic debris that would otherwise decompose in the pond water
  • Reduces the amount of work you’ll have to do in the spring when you’re ready to start using your pond again

How To Trim Foliage

To trim and remove dead or dying foliage for koi pond winterization, you’ll need a sharp pair of scissors or pruning shears. You’ll also need gloves to protect your hands from thorns or sharp leaves.

Start by trimming any dead or dying branches from trees or shrubs near your pond. Cut back hardy waterlilies just above the base of the plant. Then, remove any dead or dying leaves from the surface of your pond. Finally, trim any dead or dying aquatic plants from around the edges of your pond.

When you’re finished trimming and removing dead or dying foliage, dispose of it properly. Don’t leave it near your pond, where it can decompose and release nutrients into the water. This can cause problems with water quality and potentially harm your fish. Instead, compost it or throw it away in the trash.

Switch Over To Cold Water Bacteria

It is important to switch over to cold water bacteria during the koi pond winterization process. This helps to ensure that your pond’s ecosystem stays healthy during the colder months. Cold water bacteria are beneficial bacteria specifically designed with different strains of bacteria that can live in water that is 50 degrees and colder.

This type of bacteria is essential for the health of your pond and fish during the winter months because it helps break down organic matter. Too much organic matter can lead to harmful algae blooms and an increase in ammonia levels.

Cold water bacteria also oxygenate the water, which is essential for the health of your fish.

How To Switch To Cold Water Bacteria

The process for switching to cold water bacteria for koi pond winterization is pretty simple. You’ll need to purchase a cold water bacteria product from your local pond store or online retailer. Once you have the product, simply follow the instructions on the packaging. In most cases, you’ll need to add the recommended amount of cold water bacteria to your pond on a weekly basis.

Leave Your Pond Running

Small waterfall falling into a pond

Here in the south, koi pond winterization can be easier because you can leave your pond running through the colder months. In fact, it’s much better for your pond or water feature to run straight through rather than to be shut down. This allows your filters to keep running and keeps you from having to set up aeration and heaters.

In addition to aeration, circulation is key to maintaining water quality in your pond during the winter months. By circulating the water, you prevent stagnation and keep debris from settling on the bottom of the pond, which can lead to an unhealthy environment for your fish.

Make Sure Your Pond Fish Are Healthy

Closeup of koi fish in koi pond

If you want healthy, happy fish, you are going to need to feed them a balanced diet. During koi pond winterization, you will want to ensure that your fish are healthy before they enter hibernation.

As temperatures drop down and the pond water nears 60 degrees, the metabolism and digestion of your fish begin to slow down. Aquascape cold water fish food is what we use here at Amen Corner Ponds because it is scientifically formulated to properly nourish your fish during cold weather.

Once the water temperature drops below 50 degrees, you will need to stop feeding your finned friends altogether. They’ll soon start hibernating, which means they shouldn’t eat. Any food they eat will stay inside them until water temperatures rise and they exit hibernation.

Install An Aerator And De-Icer If Needed

This winter pond care tip isn’t necessary if you live in areas that don’t get cold enough to where the water freezes.


Aeration is the process of adding oxygen to the water. Aeration is important for koi ponds because it helps your fish breathe, making it an important part of the koi pond winterization method. When the water is cold, the oxygen in the water decreases. This can be harmful to pond fish, especially koi, which are quite sensitive to low oxygen levels.

Aerating your koi pond helps to ensure that there is enough oxygen in the water for your fish to breathe. There are a few different ways that you can aerate your koi pond. One way is to use an air pump. Another way is to use a diffuser. A diffuser releases bubbles of air into the water, which increases the oxygen levels in the pond.

Place your aerator near the surface of the water, not on the bottom. If it’s on the bottom, it’ll mix the warm and cold water together, resulting in colder water. This will make your fish uncomfortable all winter long, defeating the purpose of koi pond winterization.

Pond De-Icer

Koi pond de-icer creating a hole

In some areas, the water temperature falls low enough to where the water surface freezes. Pond contractors should know how deep a koi pond should be so it doesn’t fully freeze. A de-icer is a device used to maintain an opening in the ice that forms. This opening, or hole, allows gases that are toxic in large amounts to escape from the water. It also helps make sure oxygen can circulate so that your fish can breathe.

De-icers are thermostatically controlled. This means that they will turn on when the water temperature falls below a certain point and turn off when it rises above that point.

That’s all you need for the koi pond winterization procedure!

Get Your Pond Ready For Winter The Amen Corner Ponds Way

Winter is coming, but that doesn’t mean you have to put your pond on hiatus! With a few simple winter pond care preparations, you can make sure your pond stays healthy all winter long.

Fill out our contact form today, and one of our experts will be happy to help get your pond ready for the cold weather ahead.