Fall Outdoor Fish Pond Maintenance & Fall Garden Pond Care | How To Winterize Your Outdoor Pond

fall garden pond care ... How To Over Winter Your Outdoor Pond

Summer is now a memory and the cold days are starting to draw in ... that's right winter is on its way.

For pond keepers it is time to carry out some routine maintenance to pond keeping equipment, aquatic plants and time to be aware of the do's and don'ts of keeping fish safe and healthy over the winter months.

The fall is the time to start these tasks if you wish to maintain your pond eco system in a healthy state, ready for the new spring season

For those of you living in the Southern Hemisphere please see my Spring Maintenance Tips for your pond ...

Please be aware as you read this Autumn / Fall outdoor fish pond maintenance article that it is intended for those pond keepers who live in the colder northern US states, Canada and Northern Europe where winter temperatures often reach freezing point.

Preparing Your Submersible fish pond water pump for winter

Remove any in pond pumps (submergible pumps) and give them a thorough cleaning; be careful to remove any lime or silt build up.

Lower your submergible outdoor fish pond pumps back into the pond at a depth of no more than 1 foot, so that only the surface water is circulated around your garden pond. This will help to ensure that the warmer pond water temperatures at the bottom of your pond are not disturbed; your Koi and goldfish will find a respite in these warmer pond depths when winter kicks in. Continue to run your submersible filter pump or fountain pump until the water temperature drops to 10 C (50F).

At this low temperature there is hardly any biological activity taking place in your pond bio filter, which means that it is safe to remove the submergible pump altogether and store over the winter period, particularly if there is a chance that your garden pond may freeze over.

Introduce any outdoor fish pond pumps back into the garden pond in spring, when the biological pond activity goes mad.

Preparing Your Biological Pond Filter For Winter

In late fall when the pond water temperature drops to 10 C (50F) it is time to carry out a thorough inspection of your biological pond filter and the integrated UV sterilizer (UV clarifier) or both if you have a separate pond bio filter and UV sterilizer. Clean both thoroughly, ensuring that you back flush the pond filter, if you have pressurized filter type.

If you have a black box type fish pond bio filter then remove the pond filter media and rinse in pond water or rain water to remove the majority of the muck and sludge.

You can continue to use your fish pond water filter as a mechanical filter to remove leaves and other debris that falls into your pond; as stated earlier there is very little biological activity taking place within pond water temperatures below about 10 C (50F).

Remove the pond filter or UV fish pond filter if there is a chance that your pond will freeze over and drain it. You can store it in a safe place until spring time when it is time for it to start to earn its money yet again.

If you don't use a combined fish pond UV filter then remove the UV sterilizer (UV clarifier) over the winter period. There is no point in wasting electricity as there won’t be any green pond water to sterilize or clarify. Remove and store in a safe place until spring.

Protecting Your Pond Fish over the Winter Months

If you keep fancy gold fish such as fantails or bubble eyes then you may consider removing them from the pond environment and placing them in an indoor aquarium or pool, as they will struggle to compete with the faster moving, much more robust streamlined pond fish species such as koi, Rudd and comet goldfish for any available food.

When your pond water temperature is between 7 C and 10 C it is essential to dramatically reduce the amount of food fed to your pond fish as these cold blooded creatures are only able to digest low protein foods.

Unlike humans pond fish don't have a stomach. This means that food is digested in the colon. As the pond water cools the ability of these cold blooded creatures to digest food diminishes. If you were to feed a protein rich food in cold water temperatures you risk the chance of your fish becoming seriously ill or or dying of a compacted colon.

At these temperatures the best pond fish food to feed is a low protein content, mineral and vitamin rich fish food such as Pond Care Spring & Autumn Pond Food ... This is the best food for pond fish in colder pond water temperatures i.e. between 40°F to 70°F (5.5°C to 21°C) as the high carbohydrate and low protein diet is far easier for fish to assimilate (digest).

As a last resort wheat germ can be fed but it is not the best food for koi fish because it hardly contains any of the necessities required by Koi. As stated earlier the best koi fish food is a low protein content winter fish food, as this contains the required vitamins and trace elements to help maintain your Koi’s immune system.

At 5 C (41 F) or below your pond fish will stop feeding and start to hibernate. It is important to monitor the pond temperature accurately with a reliable Pond Thermometer so that you know when and not to feed.

If you want to know how much fish food to feed then take a look here ... how much Fish Food To Feed your pond fish.

As a preventative measure you may add some Pond Care Stress Coat to increase the slime coat of your koi and other pond fish. This slime coat protects the fish against parasites, diseases and helps to reduce stress.

Preparing Your Garden Pond Plants For Winter

As the air temperature and pond water temperature drops in the fall (autumn) it is time to get your Plant Life in order in preparation for the colder months ahead.

Cut back any Marginal Pond Plants that you have to the crown. You should have already removed lily varieties such as Canna lilies from your pond and replanted them in a green house in compost for their protection. Other lily species such as Arum Lilies can be lowered to the pond floor or replanted in planters and kept in a green house over the winter period.

It is a good idea to remove any tropical plant species if the winter temperature where you live drops below 15 Celsius (60 F) from the pond and either store them somewhere warm in compost or dispose of them.

Failure to remove tropical water plants will only add to the accumulation of pond sludge and place a greater load on your biofilter because they will die off.

For those pond keepers with small garden ponds it is advisable to cut off the heads of any marsh reeds before they shed their seeds to all 4 corners of your pond in order to propagate their species. The remaining leaves will act as a hiding place for Koi, goldfish, frogs, toads and other aquatic pond life.

It does however act as a hiding place for herons and other predatory bird species. Cutting back the marsh reeds to about 1/3rd of their original size and netting your fish pond will help to keep herons away. A strategically placed Heron Repellent will also help to keep these fish stealers away.

When your floating water plants such as pond lily pads disappear from view it is a sure sign that the cold winter months on there way. Around October time it is advisable to replant them indoors.

If your water lilies are starting to look mottled and diseased then gently remove any affected leaves to prevent them from falling to the pond floor and polluting your pond’s eco system. Your pond lily pads want as little disturbance as possible until late spring.

Move Hardy Pond Plants to deeper water.

Click here to read more about Garden Plant Winter Preparation and here to check USDA Climate Zones.

Preparing Your Pond for Falling Leaves

Biological pond filters are a necessity in garden ponds keeping fish, particularly large Koi, who produce a lot of metabolic fish waste. If on the other hand you don’t keep fish in your garden pond or have a very large pond where the shear volume of water acts as a natural eco system then any biological activity that is normally carried out by Nitrosomonas and Nitrobacter nitrifying bacteria in your pond filter will take place on the pond floor.

However when the pond water temperature drops to below 10 C (45 F) in late fall (autumn) microbial activities slow down. This happens at a time when the amount of leaves and other vegetation falling into your garden pond is at its height. This debris if not removed will sink to the pond floor.

The best solution is to remove any leaves at the pond surface using a Pond Net of some description. For those pond keepers with small garden ponds then it is advisable to cover your pond with protective netting. This will not only prevent debris from falling into the pond but will also help to keep herons and other predatory birds from eating your pond fish.

If debris has managed to fall to the pond floor then a Pond Vacuum Cleaner will come in really handy for removing organic leaves, uneaten fish food, dead algae and other debris from the pond floor.

Test Pond Water Quality

Use a suitable Pond test Kit to Test the Pond Water for pH level, Ammonia and Nitrite. Change 1/3 of the pond water as evaporation and top offs have allowed mineral concentrations to form. these need to be diluted. Don't forget to add a de-chlorinator  (tap water contains chlorine and chloramine which are lethal to pond fish).

Ideally you want the pH level to be between 6.8 - 8.0.

Use Viresco Algae & Blanketweed Remover to prevent string algae growth in the pond, on rocks and on water features and waterfalls. Viresco will also help to digest debris and organic pond sludge, making Spring maintenance a lot easier.

What Happens To My Pond When It Freezes Over?

Pond water at 4 C (39F) is somewhat bizarre in that colder water, with a lighter density is found at the pond surface whereas the warmer water remains at the bottom of the garden pond. This is the opposite of summer pond water where the warmer water is found at the surface of the pond.

As your pond freezes over there is less oxygen in the pond water and this coupled with pollutant gases released by decaying vegetation and other decaying matter on the pond floor will eventually cause fish fatalities. It is imperative that there is a gaseous exchange between the water in your garden pond and the air outside of the pond.

Many pond keepers leave a floating ball in the pond which helps to prevent the pond from freezing over totally. The movement of the ball helps to maintain this gaseous exchange. However in extremely cold temperatures this will not suffice.

The best method to stop your pond from freezing over totally is to use a Pool Heater which maintains the pond water at a desired temperature. A pool heater however can be quite expensive, depending upon the model.

A cheaper solution is to use a Pond De-icer which maintains an air hole between the iced over freezing pond surface and the air surrounding your garden pond.

Should you be in a position where your pond has frozen over totally and an air hole doesn’t exist then a quick and simple cure is to place a pan on the ice surface and add boiling water. This will cause the ice to melt. Under no circumstances break the ice cover using a hammer or other solid device as the resultant shock wave may stun your pond fish.

If you have a high fish stocking density i.e. a lot of fish in your pond then you will need to add additional oxygen using a Pond Air Pump. This will ensure that there is sufficient oxygenated pond water flowing around, should the pond freeze over.  

Winterizing Your Pond - Fall Outdoor Fish Pond Maintenance Reminder

  • Use a pond net to remove any leaves from the pond surface.
  • Cover your garden pond with a net for protection from leaves and predatory birds such as herons.
  • Remove tender pond plants indoors and replant in compost or lower them to the pond floor, depending upon aquatic plant species.
  • Thoroughly clean any submersible pond pumps and place them back into the pond at a depth of no more than 1ft, so that only the top layer of pond water is circulated. Remove your biological pond filter when the temperatures near to freezing and store away until spring.
  • Reduce the amount of fish food added to the pond and feed only low protein content fish food with added vitamins and trace elements at pond temperatures between 10 C and 7 C. Stop feeding altogether at about 6 C; pond fish hibernate at 5 C.
  • Maintain a hole in the ice surface to allow gaseous exchange to take place.
  • Keep the pool topped up especially in areas where there is a high water table. Treat any fresh water with pool conditioning chemicals.

Fall / Autumn Fish Pond Care Articles ...