How to Care for Your Pond Over the Winter...

Winter Pond Care

Winter Pond Care

The ponds ecosystem does not simply ‘turn-off’ over the winter period.  It is an integral part of the season to allow for regeneration of aquatic plants, amphibians, fish, invertebrates and bacteria.  Many problems facing hobbyists start in early spring, when after a prolonged period of sub-zero temperatures with ice and snow, often killing many aquatic plants and unfortunately amphibians and fish too, causes problems with water quality parameters and unwanted algae.

The cold does kill off many of the pathogens that frequently cause disease and death in the spring, in particular parasites and bacteria, but if your fish are not fit and well when the spring does eventually come, they will be prone to parasitic infections from low immune systems and stress from poor water quality.

In many ponds; oxygenating weed such as Elodea crispa or Hornwort which are usually some of the first aquatic plants to grow, can often struggle.  If aquatic plants are not growing in the spring you can rest assured algae will soon take hold and compete for the nutrients, resulting in an algal bloom.

Many people report large numbers of amphibians; frogs and newts found dead in the bottom of their ponds once the ice does melt.  This phenomenon is caused when ice forms a complete seal over the pond; gases that are caused from decomposing material at the bottom of the pond and ammonia that is excreted from fish and invertebrates build up to toxic levels, overwhelming fish and any frogs that may be hibernating in the water.

By preparing your pond before the winter kicks in will help to avoid these events, so outlined below are some helpful tips…


It is advisable to stop feeding fish the normal higher protein feeds when the water temperature falls below 11 degrees centigrade and feed them with a good quality Wheatgerm feed instead.  Fish are unable to digest these ‘fattier’ feeds in colder water temperatures so before they reach their ‘topor’ state (a kind of hibernation for fish when temperatures fall below 4 degrees centigrade), it is important to give their immune systems a boost, so when they come out in the spring (the same time parasites and bacteria do), they have a fighting chance of surviving and remaining healthy.

Aquatic Plants

If you haven’t already cut back aquatic plants and dead headed lilies and its still not too cold, then now is the time to do it.  This will reduce the amount of decomposing matter in the pond and in the event of the pond freezing; will reduce the levels of natural gas that builds up under the ice.  It is also important to prune back any over-hanging shrubs or plants that may block out the light, allowing aquatic weeds to photosynthesise and produce oxygen.


Most pond treatments and fish medications do not work in water temperatures below 10 degrees centigrade, so rather than wasting your money; check with manufactures prior to using.

Pumps & UV’s

If you have a pond with larger fish, such as Koi; move the pumps from the bottom of the pond so warmer water can settle at the base of the pond, providing fish and wildlife a suitable environment to over winter.  Having a pump circulating water over the winter will add important oxygen to the water and also prevent an area of the pond from freezing, allowing toxic gasses to escape.  UV’s can be turned off, but if you are also turning off the pump that runs the UV’s; ensure there is no water left inside the unit as when this expands; the ices will crack the quartz sleeves and in some units; also the outer casing.  If in doubt; check with the manufacturer.

Frozen Pond

NEVER break the ice and ALWAYS ensure that there is an area that is thawed to allow gasses to escape, even in ponds that don’t contain fish; gasses build up from rotting vegetation, detritus, microorganisms, macro invertebrates, fish and amphibians, so it is important to have an area that allows these gases to escape.  Failure to do this will often result in dead fish.  Although most amphibians such as frogs, toads and newts leave the pond over the winter, the ones that don’t will hide at the bottom of the pond and go into homeostasis; this is when the species breathe through their skin, so with a frozen pond, gasses will also kill the amphibians.  REMEMBER; smashing ice will cause shock waves that can kill fish due to the fish’s delicate swim bladder acting as a vibrating drum, you could also damage the ponds membrane making it an expensive error.  It’s also a good idea to brush off any snow from the ice so light can penetrate through to the plants.

Melting Ice

There are many methods for melting or preventing the Ice from forming that include; having a water feature or circulating pump causing moving water, a pond heater, positioning a pan of hot water on the ice, floating a football on the surface of the pond over night or positioning a length of 4-6” diameter pipe from the base of the pond leading above the surface.

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