You wake up in the morning, open your curtains and you notice your garden pond has frozen over, so what do you do.
If your pond is ornamental with no fish you can relax, stay indoors were its nice and warm as you don’t have to do anything to your pond unless you feel the need to do so.
If you want to break up the ice and remove it because you think it might damage your pond or you want to make sure wildlife can get at the water then by all means do so.
If on the other hand you do have fish in your pond you will have to brave the cold weather, put on your warm winter clothes and head out into the garden to do a bit of work.
What happens when your pond freezes over.
When your pond freezes over two things happen which will affect your fishes health, so if you want your fish to survive you need to take some action.
When the surface of the pond freezes it acts as a sort of ice cap trapping anything under the water from escaping and anything above the water from entering.
This can cause problems as organic debris and fish waste that that has fallen to the bottom of the pond releases toxic gasses which normally escape the water into the air, but if it has no way of escaping because the surface is a sheet of ice these gasses will build up making your fish ill and if left could even kill them.
Another problem is getting oxygen into the water, the same apply’s as the oxygen cant penetrate the frozen surface of your pond.
How long can fish live if your pond is frozen.
If you see your pond has frozen it doesn’t mean your fish will die, fish are cold-blooded and go into hibernation during winter months so its not the cold that kills them.
When your fish hibernate they use less oxygen to stay alive and cold water is rich in oxygen which helps them survive.
Your fish can live in a frozen pond for a few days if no action is taken but any longer and the toxic gasses will harm them, so it’s best to take action sooner rather than later.
The size of pond is also a factor, a small pond with lots of fish will suffer more than a large pond with fewer fish.
If you have a small pond with lots of fish they will all be fighting for the small amount of oxygen in the water and if the pond does freeze over the toxic gases will be more concentrated, the opposite happens in a large pond with fewer fish.
A shallow pond is going to be a lot more susceptible to freezing than a deep pond, as long as your pond is deep enough for your fish to live at the bottom without being frozen you should be fine as a pond will very rarely freeze solid.
What you should do.
To help your fish you need to make a hole in the ice to allow the gasses to escape and oxygen to enter.
You should never try to break the ice with a hammer or chisel as this cause shock wave’s in the water which will stress your fish and could even kill them.
What you need to do is melt the ice slowly making a hole around 12″ in diameter, this is large enough to allow the gasses to escape and oxygen to enter..
To melt the ice we suggest you take a pan filled with boiling water and place it on the surface of the ice and let it melt through the ice, a hot water bottle will also do the trick.
There are suggestions of pouring boiling water straight onto the ice and although this will melt the ice quickly we feel that the boiling water might mix with the cold pond water heating it up a bit which might confuse you fish, so we would stick with the pan option.
Once you have made a hole in the ice you need to check twice a day to make sure it hasn’t sealed over, if it has, slowly melt the ice again.
Can you prevent your pond from icing over in the first place.
Yes there are a few things that you can do to prevent your pond freezing over.
Running your pond pump through the winter keeps the water moving which can help to stop water icing up.
A floating pond de-icer/pond heater will supply enough concentrated heat to keep a hole open, it floats on the surface of your pond but will not heat up your pond, it just stops the ice forming around it and letting the toxic gas escape.
If your pond has frozen over you can lay a de-icer on the ice and it will melt the ice and then drop into the water, de-icers are run on electricity so you do need a supply close by.
A submerged pond de-icer/pond heater sits on the bottom of your pool and it’s a good idea to use one if you have a shallow pond of less than 18″ as this will stop your pond freezing solid and protect your fish.
Although using one doesn’t always protect your ponds surface from freezing over so keep an eye on it.
You could use an aerator which sends bubbles to the surface which can help with ice forming, these are great to use with a de-icer.
An aerator also has the ability of further increasing the oxygen levels and removing harmful gases, just place it about a foot below the surface, you don’t want to place it on the bottom of the pond as this could affect the natural water temperatures.
These are cheaper to run than pond de-icers so you could run one of these to stop ice forming and use a de-icer as a back up if your pond does freeze over.
An inline pond heater can be used which can be set to a temperature so it only comes on when the temperature drops but won’t come on heating your pond when the temperature is above freezing, but we don’t really recommend using one as it’s is not necessary unless you have expensive Koi that you want to protect.
You can also cover part or all of your pond with an insulated cover.