Pond Heater or Pond De-icer: How they work and do you need one.

pond heater de-icerPond heaters and pond de-icers, what’s the difference. 

This is where it can get a bit confusing, some people refer to a pond heater as a de-icer and others refer a de-icer to pond heater but who is right.

Now you could say they are the same thing and when you go to buy one it’s possible you could see the same type of product but one called a heater and one called a de-icer or even a heater de-icer.

Two different names but do they do the same job.

There are three types of heater/de-icer that you can purchase but in my mind only one of them is an actual de-icer, read on and I will try and explain.


Floating pond heater/de-icer.

This is the one I think should be called a true de-icer.

Many people search for a pond heater but in reality what they really should be searching for is a pond de-icer.

As you can see from the Hozelock pond heater above which I found on Amazon.co.uk it markets it as a pond heater when I would call it a pond de-icer.

The purpose of a floating de-icer is to stop the surface of your pond from freezing over.

It doesn’t stop the whole pond from freezing and is not designed to keep the pond water warm it just keeps a small hole open.

Having a small hole open in a frozen pond is vital to to your fishes health.

When a pond freezes over the toxic gasses that builds up from decaying matter and fish waste that has collected at the bottom of your pond is trapped beneath the frozen surface which acts like an ice cap, if these toxic gasses are allowed to build up your fish will get sick and could die.

Having a hole in the frozen surface also allows oxygen into the water.

The floating de-icer runs on electricity so you need a power supply close by to use one.

They work by floating on the surface of the water creating a small area of warmth around the heating unit which stops the surface around the de-icer from freezing over.

If your pond has frozen over you can actually place a pond de-icer on top of the ice and turn it on, it will slowly melt the ice for you and eventually drop into the water once the ice has melted and then carry on doing the job it is meant to do.

The cost of running one depends on the wattage of the unit you buy but as they are temperature programmed they only turn on when it hits a certain temperature so it all depends on how cold it gets and how often it turns on.

Do not panic and think all your fish are dead if one morning you find your pond frozen, fish can survive under the frozen ice for a couple of days but I would not leave them too long.


Submerged pond heater/de-icer.

Now these submerged heaters are often marketed as de-icers but to me that’s not their purpose.

As the name suggest these heaters are placed on the bottom of your pond where it warms the water.

They will stop the water at the bottom of your pond from freezing, but they might not stop the surface from freeing because they don’t generate enough heat.

If you have a deep in ground pond the water at the bottom is insulated from the soil around it so it’s very unlikely it will freeze, if on the other hand you have a shallow pond of  less than 18″ then there is a possibility it could freeze so these heaters can be of great value if you don’t want your pond freezing solid.

These type of heaters can be used in conjunction with floating de-icers if you notice the surface of your pond is freezing up.


Inline pond heaters.

This is what you call a true pond heater, this type of heater is used in conjunction with your pond pump.

Water flows through the heater heating up the water before being pumped back into your pond.

These are not really used as a method of de-icing your pond although if you have warm water there is less likelihood of it freezing in the first place.

These are very expensive to run and are usually only used by owners of exotic tropical fish.


Do you need a pond heater.

If you don’t have fish in your pond or you live somewhere that your pond doesn’t freeze over during the winter you probably don’t need a pond de-icer/heater.

During the winter your fish will hibernate in the deepest part of your pond where it is warmest so as long as they can get oxygen and there is no build up of toxic gasses they will be perfectly happy.

If your pond freezes a floating pond heater/de-icer is a great way to keep an opening in the ice that lets toxins out and oxygen in.

Running your pond pump on a reduced flow rate recirculates the warmer water from below the surface and keeps the water moving, just raise it of the bottom of the pond so it doesn’t draw the water up from where your fish are hibernating keeping that area of the pond warmer.

If you have a waterfall leave it running, the water falling of the edge of the waterfall will keep that area from freezing up.

Be aware if the water on the waterfall starts to freeze up, this could cause a dam stopping the water getting back into the pond instead it will overflow into your garden emptying your pond at the same time.

Covering or part covering your pond with an insulating cover can help and if your good at DIY you could knock one up yourself.

There are less expensive ways of keeping an opening in your ice such as aerators and floating ice preventer.

You can also visit your pond twice a day to melt the ice away, do not break the ice as the shock waves of all that banging on the ice can cause stress to your fish and even kill them.

Instead, fill a pan with hot water and place it on the surface of your frozen pond to slowly melt the ice leaving a good sized hole.

At the end of the day as long as you can keep your pond’s surface from freezing over or just having a hole to let the bad toxins out and oxygen in your fish should survive the winter and be healthy and active when spring comes around.