Gardening tips, advice and ideas

5 Best Pond Heaters / Deicers – Overwinter your Pond and Fish

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You work hard to give your fish a clean and healthy pond environment. So install a pond heater deicer to make sure they don’t freeze in the winter. I review heaters that warm up much of the water in your pond as well as deicers that heat just a localised area of your pond’s water and thaw out a small area of surface ice. Knowing which type you need is what really matters.

Pond prevented from freezing over to protect koi during freezing temperatures

I list the pros and cons of each product along with a short discussion of the features before I give my recommendation. My Buyer’s Guide identifies the differences between pond heaters and pond deicers and describes the benefits of each and which you probably need.

Best Pick – Pond Deicer

Finest-Filters Floating Pond Heater - 150W
This floating deicer does its job of warming a small portion of your pond well. In doing so, any ice above this unit melts, allowing fresh oxygen to dissolve into the water and toxic gases to escape - all for the benefit of your fish and pond ecosystem. The 5 meter electric cord gives you some freedom about where in the pond to create this warm spot for your fish to congregate in the cold months. As well as the 150W model we review, this item also comes in a 300W model and in a 600W one. This is a small investment to keep your pond (and fish) healthy during colder months.

Best Pick – Pond Heater

Cloverleaf PHEAT2KW 2KW Pond Heater
For raising the temperature of all the water in your garden pond, the Cloverleaf PHEAT2KW 2KW Pond Heater has a thermostat you can set from 0°C to 45°C. Once you've set this unit up in your pond circulation system (i.e. attach it to your pond pump) and switched it on, the heater automatically clicks on when the pond water around it falls below your selected temperature. This pond heater comes with a large variety of connectors to other pond equipment pieces so you can be sure that it fits in with your existing set-up. This is a versatile pond heater that keeps your entire pond warm and free from ice.

Best Pond Heaters and Deicers reviews

1. Finest-Filters Floating Pond Heater

Best Pick – Pond Deicer

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Finest-Filters Floating Pond Heater for Koi Fish Pond Anti Ice Winter 150/300 / 600w (150w)

This Finest-Filters Floating Pond Heater for Koi Fish Pond is actually a floating decicer for keeping ice off a portion of your pond and by warming the water below. This creates a nice warm space for your koi and other fish in the pond. Plus keeping the water surface open allows that water to oxygenate bring much needed fresh oxygen to your fish and allowing a space for toxic gases to be released.

The long stainless steel heating rod hangs beneath some floating foam disks. This 150W  model has three such disks to fully keep this deicer afloat. The power cord comes out the top of the rod and through a hole in the floating discs, handy for you to then plug it into your outside power outlet. With 5m of power cable, you can possibly put the deicer in open water, away from the side of your pond or wherever your fish prefer to hang out.

This 150W model is suitable for ponds up to 10,000L in size – though bear in mind deicers only warm a small section of this. This model also comes in a 300W model for ponds 10,000L to 20,000L and in a 600W unit for ponds larger than 20,000L (this one comes with four floats).

I also found what seems to be a very similar model for a similar price (as at January 2022), Hepo Pond Heater Floating for Koi Fish Pond.

Pros

  • Floating pond deicer to keep part of your pond from freezing in the winter.
  • Long stainless steel heating rod hangs in the water below foam floats.
  • Outside rubber power cable is 5m long.
  • 150W model comes with three foam floats which you stack together for the best floating.

Cons

  • No thermostat.
  • No “Working OK” indicator.

Our recommendation

The Finest-Filters Floating Pond Heater for Koi Fish Pond is a deicer that comes in a variety of power outputs – 150W, 300W and 600W. The generous 5M power cord gives you some leeway in where in your pond you place the deicer. But be sure to plug it into a certified outdoor power outlet.

The Finest-Filters Floating Pond Heater for Koi Fish Pond is my Best Pick – Pond Deicer in this review.

Have you considered a pond vacuum to help clean your pond?See my top recommended pond vacuums here


2. Cloverleaf PHEAT2KW 2KW Pond Heater

Best Pick – Pond Heater

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2KW Pond Heater with Thermo Control

The Cloverleaf PHEAT2KW 2KW Pond Heater is indeed a water heater as it heats all the water pushed through it by an existing pond pump that you supply. It’s not an immersed heater though it does have a waterproof rating of IP55. This means that its protected from low pressure water jets, so certainly from any spray that comes off your pond and most light rain storms.

This is a pond heater that fits into your existing pond pump and filter system. The input and output pipe connections can be flexible or rigid. So it fits a variety of set-ups. Attach flexible hoses of 19mm, 25mm, 32mm or 38mm diameters or rigid solvent pipe of 40mm diameter.

The minimum flow rate through the heater is 4,000L/hr. You use the low pressure flow switch to get this. Otherwise, the heater can handle higher flow rates. Just check how much water your pond pump puts out.

You’ll need to do some further research as to where in your pond filtration system to place the heater (before or after the filter) as the manufacturer doesn’t make any recommendations on their website.

The thermometer control on this PHEAT2KW heater is a dial that you turn to select the temperature. It ranges from 0°C to 45°C. This 2kW heater can handle a pond of up to 9,000L. For a smaller pond, take a look at the 1kW model in the same style.

Pros

  • Pond heater with thermostat control from 0°C to 45°C.
  • Waterproof rating is IP55 / IPX5 – protected from low pressure water jets.
  • Power cable is 1.5m long.
  • Pipe connections can be rigid or flexible.
  • Minimum flow rate is 4,000L/hr.
  • Has a low pressure flow switch.
  • 2kW model is suitable for a 9,000L pond.

Our recommendation

The Cloverleaf PHEAT2KW 2KW Pond Heater heats water that flows through it from your pond pump and discharges the warm water back into the pond to circulate. This unit sits on dry land though it is waterproof to water sprays and light rain. You can attach flexible hoses or rigid tubes to the case of this heater so it fits into a wide range of existing pond pump and filtration systems.

The Cloverleaf PHEAT2KW 2KW Pond Heater is my choice for Best Pick – Pond Heater.

Also, consider getting yourself a good water pump for emptying your pond when needed – see my top rated dirty water pumps for emptying ponds


3. Superfish Pond Heater 150 Watt   

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Superfish Pond Heater 150 Watt

The Superfish Pond Heater 150 Watt  is a pond deicer so it floats in your garden pond. Its purpose in life is to heat up a small area of water in your pond and to keep the matching surface of the pond ice free. I couldn’t find any information about how large an area this covers but some online reviewers report that all their fish are able to gather in the warm zone.

This deicer consists of a stainless steel heating rod suspended from a floating foam disk. The power cord is attached to the centre top of the disk. It all floats in the water where the electric cord is generally stable enough to keep it from drifting about. Plus at 5m long, the cord lets you place the deicer away from the edge of the pond, towards the open water.

There’s no thermostat or timer on this deicer, so it needs to be left on to keep working. But you only need use it when the temperature of the water falls below the optimum heat for any fish you have there.

Even without fish, it’s important to keep an area of your pond ice-free so fresh oxygen can dissolve in the water and toxic gases can leave. This keeps your pond healthy throughout the cold months.

Pros

  • Floating pond heater has a straight stainless steel heating element below a floating Styrofoam disk.
  • Uses 150W to heat the water.
  • Heats the water around the heating stick.
  • Creates a hole in any ice formed on the surface of the water.
  • Outdoor power cable is 5m long.

Cons

  • No thermostat.
  • No “working OK” indicator light.

Our recommendation

The Superfish Pond Heater 150 Watt is really a deicer designed to warm a small part of your pond and keep ice away from the surface there. This allows oxygen to enter the water and harmful gases to leave. Plus it creates a warm zone for your fish to mingle in while breathing easily. I like the long 5m power cord that gives you some freedom as to how far into the pond you want to place the deicer.


4. Blagdon Affinity Ice Vent Pond Heater

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Blagdon Affinity Ice Vent Pond Heater, Allows Oxygen In, Toxic Gases Out, Allows Fish to Breathe, for Ponds up to 5000 Litre

The Blagdon Affinity Ice Vent Pond Heater is a pond deicer that heats a small section of your pond and keeps the corresponding surface clear of ice (before and after it forms). This model is slightly different to the other deicers I review in that, instead of a long heating rod, it has a convection design that is stated to save energy. This is useful if you plan to leave the deicer on all the time in the winter as it has no thermostat to control an On/Off cycle.

This all-black unit has a disc on top that floats and a black column underneath. The unit works by water entering in at the base of the column, being heated and then rising up the column to exit back into the pond at the top. There’s a cavity on the top of the floating disk to let fresh air in to oxygenate the water and to let harmful gases out. The width of the cavity is the area that’s kept ice free.

Blagdon Affinity Ice Vent Pond Heater, Allows Oxygen In, Toxic Gases Out, Allows Fish to Breathe, for Ponds up to 5000 Litre

The 10m power cord runs from under the floating disk.

Im not sure why the manufacturer says that this unit works for ponds up to 5,000L in volume as its intended to heat only a small area. But they also state that you can use more than one of these units if you have a larger pond, so keep that in mind. Of course, you can also do the same if you want to have several warm places for your fish to shelter in in winter.

 Pros

  • Floating pond deicer suitable for ponds up to 5,000L.
  • Heating element in long convection chamber below a circular floating platform.
  • Stops the water surface from icing over and freezing.
  • Low wattage convection design for efficiency and effectiveness.
  • Power cord is 10m long and the unit operates at 50W.
  • Suitable for use down to -10°C.
  • Two-year guarantee.

Cons

  • No “working OK” indicator light.
  • No thermostat.

Our recommendation

The Blagdon Affinity Ice Vent Pond Heater is a deicer that works by the convection method. Water is taken in cold to the heating element, heated and then rises along the tube and out the top. This is said to be more energy efficient than other styles of deicer, an important consideration if you plan on keeping this unit on throughout the winter.


5. AquaForte Professional Pond Heater (1 KW)

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Professional Pond Heater 1 KW) 5000 L / Heater for Heating ponds

The AquaForte Professional Pond Heater (1 KW) is a pond heater for the entire pond, and needs a pond pump to operate (supplied by you). The pump pushes the water through the unit where it’s heated and then returns to the pond to circulate. The warm circulating water raised the temperature of the water in the pond and prevents ice forming.

This model comes with a variety of different connectors to connect into a range of different pond pump and filter systems. There are connectors for flexible hoses of 25mm, 32mm, and 40mm diameter and fittings for rigid PVC pips of 50mm and 63mm. This covers most of the popular pump, filter and aerator units available for ponds.

In this case, it makes sense that the manufacturer tells you how large a pond this heater can heat. This 1kW model works in ponds up to 5,000L; there’s a 2kW model for ponds up to 10,000L; and large ponds up to 15,000L are provided for by the 3kW model.

Unfortunately, I couldn’t track down any information about the length of the power cable, not even on the brand’s website. But I did find out that this heater has a thermostat that goes up to 40°C to keep your fish warm and any ice from forming by automatically kicking in the heater when the water temperature drops.

Pros

  • Pond heater warms the water and prevents ice from forming.
  • Two connection points and a variety of connectors.
  • Suitable for ponds up to 5,000L.
  • Thermostat up to 40°C.

Cons

  • Need pond pump to work with this.
  • Power cable is of unknown length.

Our recommendation

Despite being short on information on the manufacturer’s website and sales site, the AquaForte Professional Pond Heater (1 KW) is from a brand renowned for its pond supplies. And that’s why I include it here. I like that it has a thermostat that goes up to 40°C and that it comes with a range of fittings to hook it into your existing pond system.


Buyer’s Guide for Pond Heaters and Deicers

While pond heaters and deciers work differently, they do have the same purpose: to maintain a healthy temperature and environment in your garden pond throughout colder months. They do this by increasing the oxygen content of the water (which generally falls during the wintertime), allowing toxic gases to continue to release from the pond, and making your fish more comfortable as they hibernate. It’s the way they do this that’s different.

Note: whichever pond heater or deicer you purchase, don’t be surprised that there’s no plug attached. Regulations in the UK prohibit outdoor appliances from coming with an (indoor) plug as they’re supposed to be hardwired into a consumer unit or RCD.

koi fish pond need pond heaters to help keep them healthy over winter

Floating electric pond deicers

During colder times your fish aren’t too active so they don’t need the full run of the pond to be happy. Pond deicers are a popular line of pond heater as they’re relatively inexpensive to run. These devices heat only a small area of your pond – they warm water that’s within reach of the heat output by the vertically floating heating rod.

Deicers aren’t designed to increase the pond water temperature as such, but to warm it enough to keep the surface ice-free and provide a slightly warmer haven under the floating disks for your fish. The open water area lets oxygen into the water while the open space is also an opportunity for toxic gases, which always build-up, to escape. Your fish breathe fresh oxygen and don’t suffocate on toxic gas; your pond bio-environment, in general, remains healthy.

Pond deicers don’t come with a thermostat so they’re either on or off. And you determine this by either plugging them in or unplugging them. You may want to run a deicer continually on colder days and weeks, so check the watts of the model you buy to see how much your power bill will go up.

Pond which uses pond heater to stop it freezing over in winter

Electric pond heaters

The idea with electric pond heaters is to raise the temperature of the water in the pond a few degrees, which can make a huge difference to the fish in your garden pond. Of course, this also serves to keep ice off the surface as well.

The electric pond heaters I review are designed to be part of an existing pond circulation system. They need at least an external pump to send water through them. While the water is inside, it’s heated, and then emerges to circulate in the pond.

If you also have a filter and/or an aerator in your pond system, it’s up to you to decide where in the system you want to place the pond heater. The heater does need to be separately plugged into an electric outlet as most have a thermostat which kicks in when the water temperature drops below the temperature you select.

Experts advise placing the heater as deeply in the pond as you can so you avoid heat loss of water at the surface of the pond.

Just a note: electric pond heaters can be expensive to run. Some online reviewers suggest insulating your pond in the winter to preserve whatever heat is generated in the water.


Final Conclusion

Keeping the fish in your garden pond warm and healthy throughout the colder months only takes some forethought on your part, plus a pond heater deicer. Getting fresh oxygen into the pond water continually is the key here, whether you choose to heat much of the pond water or just a small space where your fish can congregate. All the models in our review work alongside or in the system with any other apparatus you’re using to keep your pond clean and ventilated, such as a pond pump with built-in filter or a pond aerator.

My Best Pick – Pond Heater is the Cloverleaf PHEAT2KW 2KW Pond Heater. This heater works on the water in the entire pond and has a thermostat that goes up to 45°C.

The Finest-Filters Floating Pond Heater for Koi Fish Pond is our Best Pick – Pond Deicer in this review. This model comes in three different power sizes, depending on how much water you want to warm up.

Your winter tasks don’t end with your pond. Check out our Best times to water your garden in winter – Our top 6 winter watering tips for great advice.

And don’t forget about the birds – Choosing the best food for garden birds in winter and helpful tips to help over the colder months on the year.


Last update on 2022-03-17 / Affiliate links / Images from Amazon Product Advertising API

Welcome to my site, my name is John and I have been lucky enough to work in horticultural nurseries for over 15 years in the UK. As the founder and editor as well as researcher, I have a City & Guilds Horticultural Qualifications which I proudly display on our About us page. I now work full time on this website where I review the very best gardening products and tools and write reliable gardening guides. Behind this site is an actual real person who has worked and has experience with the types of products we review as well as years of knowledge on the topics we cover from actual experience. You can reach out to me at john@pyracantha.co.uk

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