How to

12 October 2016

How to Keep Your Garden Pond Ice-Free This Winter

As temperatures begin to drop towards freezing point, ice becomes a common winter frustration for many a keen gardener. If your carefully planned out garden contains a pond, particularly one containing fish and other wildlife, this minor inconvenience can become a major annoyance, as toxic chemicals can build up below the surface, posing a threat to any wildlife that may be present. As such, keeping a least a small portion of the pond ice-free is vital.

There are many sworn-by methods of alleviating this problem, but some pond owners are unwittingly causing harm in the way they go about it.

For example, one common method of de-icing a garden pond is to use a hammer or similar tool to crack the ice by force. While this will, with much effort, eventually break through the ice, the shockwaves caused by the striking motion can actually harm the fish and other wildlife that calls your pond home. Other people suggest introducing salt or oil to the water in order to prevent freezing, but I’m hesitant to endorse any approach that involves filling the water with contaminants of any kind. Even if the potential for damage is minimal, it’s still better to avoid the use of chemicals and pollutants. After all, they’re called freshwater fish for a reason.

So, how can you go about de-icing your pond, or preventing it from freezing in the first place, in a safe, efficient manner?

The obvious solution is to invest in a pond heater or an ice preventer with an incorporated air pump. While both of these will help in preventing the ice from covering your pond entirely, they do so in very different ways.

On the subject of heaters, I’m not suggesting a massive heating rig designed to regulate temperature across the entire pond; such heaters are expensive both in terms of initial investment and running costs, as well as being highly inefficient and not really necessary. As previously stated, only a small portion of the pond needs to remain ice-free in order to allow the movement of oxygen and toxins, and there are many small-scale pond heaters designed to do exactly that. These heaters are essentially just a simple heating element attached to a float. The device sits just below the surface and keeps a small area of surrounding water in liquid form, more than enough to ensure a healthy habitat. Some of these heaters, such as the 'IceFree Thermo' (pictured), even come fitted with temperature sensors which allow them to activate themselves only when temperatures are low enough to require it, saving substantially on running costs.

In the case of ice preventers, these work not by heating the water, but by keeping it in a state of perpetual motion. This fights the formation of ice in a couple of ways. Firstly, the constant mixing of the water means that it cools at a more uniform rate across the entire body of water, making it more difficult to reach low enough temperatures for freezing. Also, the movement itself prevents the water molecules from crystallising, a vital part of the process of ice formation.

If you would rather avoid spending the extra money, the DIY approach can be surprisingly effective if done right. Many people choose to cover their ponds with heavy tarpaulin or bubble-wrap during the winter months, insulating the surface from the outside air. This does undoubtedly work, but there are more time-efficient approaches you can take.

Probably the best bit of advice I have found while doing research for this article is also by far the most simple, and as an extra bonus, the cheapest! All you need is an inflatable ball or two, around the size of a football or volleyball. Simply leave these floating around the surface of your pond (the number required will of course depend on the size of your pond) and they will prevent the formation of ice by keeping the surface in motion, working in much the same way as the ice preventers mentioned previously, but bypassing the need for any extra expenditure.

If your pond has already frozen, in which case the above advice is of little use to you, placing a saucepan of boiling water on the surface of the ice will melt an ideally-sized hole, although you do then have the ‘joy’ of trying to recover said saucepan from the cold waters.

Side Notes:
  • In order to avoid any potential damage, it is recommended that you remove the filter from your pond over winter. These filters are easily damaged by ice, and are not really required during the winter as less activity on the wildlife’s part results in fewer harmful nitrates building up in the water. The hole you have just created in the ice is enough to maintain a healthy ecosystem.
  • Depending on the species contained within your pond, it may also be a good idea to turn off the pump. This will create a layer of warmer water at the bottom of the pond, where most fish will reside during the winter months.

Sam Bonson

Sam is an aspiring novelist with a passion for fantasy and crime thrillers. He is currently working as a content writer, journalist & editor in an attempt to expand his horizons.