A pond in the garden is the absolute dream of many garden lovers. More and more of them are realizing it. Fish and other creatures are often simply part of the pond. A garden pond can become a deadly danger for them in winter, namely when it freezes over. Then there is no more new oxygen for the aquatic life. you suffocate. It doesn’t have to be. There are different ways and means for an ice-free pond. The entire surface does not have to be kept ice-free, one opening is usually sufficient. So there are no problems with oxygen and there are no toxic fermentation gases.
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Observe the minimum depth
The larger a pond, the fewer problems there are with freezing. However, there is often no space at all for a larger pond in the smaller house gardens, a small one has to suffice. This freezes over quickly, especially if it is not deep. Ponds with a depth of less than 80 centimeters quickly freeze over.
Keeping larger ponds free of ice is quite easy. You need a larger number of aquatic plants that protrude above the water even in winter. This not only looks nice, it also ensures that the ice surface has a leak. The dangerous fermentation gases can escape and oxygen gets into the water.
“Home remedies” for an ice-free pond
You often don’t have to dig deep into your pocket to keep your pond free of ice.
- A piece of wood
- A rubber ball
- A big branch
- A bundle (30) of thin bamboo sticks tied together and placed in the pond
- PE balls, the balls filled with air, can help to ensure that the pond water does not cool down too much. 1,000 balls cost around 30 euros, 10,000 around 180 euros. This allows a fairly large water surface to be kept clear. The balls come in different colors. The transparent balls are transparent, so daylight can penetrate.
You can achieve a lot with such simple tools. A piece of wood or a rubber ball can be doused with hot water more or less regularly when the temperature is below zero. This creates an area free of ice sufficient for oxygen to enter the pond. If the rest of the pond is frozen over, it is extremely useful to take water from the open area to create a void between the ice and the water surface. This is ideal for aerating the pond and the space also serves as an air and oxygen reservoir.
A thick stick stuck into the pond also keeps the ice open. There you only have to stir the water once or twice with it in frosty weather. That helps a lot with small ponds.
Technical assistance to keep ice free
With larger ponds and a higher fish stock, it often makes sense to use an ice preventer or a pond heater. A pond heater works best, it doesn’t matter how long the cold period lasts or how low the temperatures drop. If the heating system is intact, nothing can happen. An ice preventer is not quite as reliable. Oxygen stones are also helpful. Depending on the pond size, several stones are required. If they are not installed too high or too low, they also create one or more open spots in the ice. They create oxygen bubbles. As a result, the water around them keeps moving and no ice forms there.
ice preventer
Ice preventers are simply placed on the water surface. They are lightweight, made of styrofoam with ventilation slots and float on the water. One keepers only keep a small area of the pond open. They are often offered with a ventilation pipe. With these models, an air bubble is created in the styrofoam housing. The air is therefore warmer than the outside temperature and the pond cannot freeze over. These models do not require a power supply and cost from around 10 euros. The devices should work down to -20°C.
Those with a cable connection are slightly higher in price, simple devices are available from a good 15 euros, most cost around 35 euros. As a rule, the power is 5 watts, which is reasonable in terms of consumption.
Ice preventers with an integrated frost monitor function switch on automatically when there is frost and keep the area around the device free of ice. The resistance heating technology should ensure higher performance in the freezing area and protection against temperature damage. On warmer days, the device switches itself off, so it does not consume any electricity. The devices have 330 watts, so they consume significantly more energy. This frost monitor is said to be effective down to -20°C.
Free guards are only suitable to a limited extent for longer periods of frost. Then a pond heater is the better choice. Nevertheless, there are good ice preventers. I find the ones where you open the lid and fill in sand or gravel ideal. This prevents the “device” from being blown away in the wind, which Styrofoam tends to do unless you have an anchor. There is also the variant. In any case, an ice preventer should be placed over the lowest point in the pond.
If you want to build a reliable ice preventer yourself, we recommend the website www.jonas-familie.de/hobby/garten/gartenteich/eisfreihalter.htm.
pond heating
Pond heaters are something like immersion heaters. However, they only switch themselves on when it is freezing and switch off again when the temperatures are milder. But they have a higher power, about 150 watts. The heating rod, which is in a styrofoam cover, is simply placed on the water surface. The built-in frost monitor then generates heat in the heating element when required, thus preventing the pond from freezing over.
Another possibility is heating based on the principle of a flow heater. Water that comes out of the pond filter is heated in the instantaneous water heater and this prevents the water temperature in the pond from falling any further. Here, too, a thermostat regulates switching on and off. There are different power ranges, 150 and 300 watts. Very well equipped pond heaters are still equipped with a flow pump. This ensures water movement around the heater. This keeps the water surface even more open.
Pond heating cables can also adjust the water temperature. They are available in different sizes, depending on the size of the pond. They have quite a lot of watts, 300, 480 and more. The cables are not cheap (starting at around 60 euros and the thermostat costs extra, also around 50 euros. You can buy a complete pond heater with flow pump right away. They are in a similar price range.
But a pond heater has another advantage. Pond fish, especially koi, often react very sensitively to strong and rapid temperature fluctuations in the pond water. If you want to keep the temperature constant, a pond heater is a great thing. To do this, however, the heater must have a thermostat, which automatically and reliably ensures a constant water temperature.
As an alternative, I have found that an aerator/air stone (a membrane pump with 10 watts) can be used. This is a good and, above all, inexpensive option. These aerators are available from 10 euros. They are hung about 30 centimeters below the water surface. There is a hole in the ice above it.
Pond aerator – oxygen stone
Pond aerators ensure the oxygen supply in the pond. A sufficient supply of oxygen, mainly through the pump, should prevent the pond from completely freezing over. There is always one vacancy. There are different models, depending on how high the air flow rate is. So it depends on the size of the pond, the cubic meters of water that are in it. Prices start at around 50 euros.
Pond aerators are only necessary if fish live and overwinter in the pond and if there are not enough pond plants to provide oxygen. They are ideal for plantless koi tanks. Aeration can also be used to improve filter performance.
The pond aeration consists of an air pump, usually a diaphragm or piston pump, and an air vent. This ensures that the air bubbles flow out into the pond water. They should be as fine as possible.
In summer, the plants are busy producing oxygen. Pond aeration is hardly worthwhile. Things are different in winter. The filter circuit has to break down the nutrients. Bacteria have settled in the pond filter to help with this.
Pond aerators that use Venturi nozzles for air supply are ideal. You do not need a power connection, but pull the air into the water via the current.
Oxygen stones are already available for a few euros.
Pond frozen – what then?
If, despite everything, the pond freezes over, after all, any means can fail, you should not use force and simply hack open the ice surface. Not only does this startle the fish, the sound waves it creates can cause the fish’s swim bladder to burst. That usually means their end. So always be careful and defrost slowly, for example with hot water.
Conclusion
Anyone who owns a garden pond and wants to overwinter fish in it must ensure that the pond does not freeze over completely. If the pond is sufficiently large and, above all, deep, this is usually not a problem, especially if there are enough plants in it. Small ponds are a bit more difficult to handle. Ice preventers are a useful way of keeping a spot in the ice clear, but they do not work at very low temperatures and not in long-lasting freezing cold. But you can combine them with one or more bubble stones, which significantly increases the chance of a hole in the ice. If you want to be on the safe side, use a pond heater. They are still acceptable in price. The safest way is a normal pond pump that works all year round. However, not every pump can be used for winter operation and low temperatures, there are special devices for this. However, they are significantly more expensive than all the options listed here for keeping the garden pond free of ice.
