Best Pond Heater and De-icer

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koi pond covered with ice

1. Aquascape 39000 Pond Heater and De-icer – Best Overall

The Aquascape 39000 is precisely what most people need to keep a nice bit of their pond de-iced in the winter. It’s a robust unit, made of stainless steel to prevent corrosion and other chemical damage. That’s important for a unit that’ll be in the water.

This model packs about 300W, which is enough to keep a hole in the ice through most conditions. You may need to size up for ponds that are exceptionally deep or over 1000 gallons but it’s perfect for the vast majority of ponds.

It also has a nice little LED indicator to let you know it’s working at a glance, rather than just hoping it’s still on. It’s a little touch but being able to see if your pond heater without running out into the cold.

This unit is a bit on the pricier side, which is understandable given its construction. It also appears to have some issues with longevity, most seem to last only two or three years.

Bottom line is that this is a great choice for a de-icer. It’s just a bit expensive for it’s class, mostly due to the stainless steel construction.

Pros

  • High wattage for de-icer
  • Stainless steel construction
  • LED indicator light
  • Good for up to 1000 gallon ponds

Cons

  • Expensive
  • Some only last a few years

2. Finnex Digital Heater Controller – Best Submersible Pond Heater

For keeping small ponds heated year-round, Finnex makes this neat little heater that ranges up to 800W and is suitable for smaller ponds. It features a titanium tube and robust construction. It’s actually designed for outdoor use, so it’s much better than trying to adapt an aquarium heater.

The 800W heater should be good for ponds up to 500 gallons or so, but you may need more than one if you have exceptionally harsh winters. The neat part is that the system is designed with switchable tubes, allowing you to go up or down if you don’t have the right initial wattage.

This one comes with a great control set, which allows precise temperature adjustments. This makes it suitable for things like tropical fish ponds, where you may need to be more precise than “warm.”

What this heater isn’t suitable for is larger ponds. It also has a 2° tolerance for the controls and they’re hard to calibrate properly. The biggest problem is that you’ll have to find or create your own mount to keep the heater safe.

Despite the minor drawbacks, this submersible heater is a lifesaver for smaller ponds. The adjustable heater wattage is nice and it has great controls. There’s not much more you can ask for in a submersible.

Pros

  • Great controls
  • Interchangeable system to change heater wattage
  • Easy-to-use
  • Durable titanium construction

Cons

  • Not suitable for large ponds
  • No mounting hardware included

3. Farm Innovators 617407735932 Model P-418 – Best De-Icer for Large Ponds

Large ponds have limited options, especially if you’re not going to install an inline or gas system. A lot of de-icers just won’t keep up when your pond gets larger, which is where this 1250W heater comes in.

This is closer to a commercial quality heater. It’s robust, simple, and has thermostatic controls for a bit tighter leash on the heat. It’s also reasonably priced most of the time, rather than being a wallet breaker.

These units can handle heavy use and are a good option for smaller ponds in extreme climates. They seem to be able to hold a hole in a 500-gallon pond when the weather is below freezing, which is pretty impressive.

Unfortunately, like most de-icers, it suffers from a lack of longevity in some cases. The installation instructions are also a bit extreme, but you’ll need to go through with them to keep the heater in warranty.

For large ponds or small ponds in extreme weather, this 1250W heater is perfect. Just make sure that it’s installed properly for the best results.

Pros

  • Very powerful for a de-icer
  • Aluminum construction
  • 10-foot cord
  • Reasonable price

Cons

  • Longevity and reliability issues like all de-icers
  • Installation is a bit intensive for this type of heater

4. TetraPond De-Icer – Best Hidden Pond De-Icer

Most pond de-icers are a bit unsightly, but the Tetra Pond De-Icer is designed to look like a floating rock. It’s not a perfect disguise, but it’s more attractive than staring at a stainless steel bell all winter.

This is a 300W heater, perfect for smaller ponds but not enough for large ones. It also comes with a 15-foot cord, which is 50% longer than the industry standard!

Tetra states that it will work as low as -20°F, which is probably true in smaller ponds. The shutoff point seems to be at about 90°F, so it will keep the water warm if it can.

Because of the high thermostat, this de-icer may not be a good option for very small ponds. Anything under 300 gallons may end up a bit too hot. Like all de-icers, it appears to have longevity issues, so remember your three-year warranty.

Overall, this is a great little de-icer for those who want to maintain a natural look in their pond through the winter. It’s worth a look for ponds in the 300-600 gallon range, but it’s not the right choice for everyone.

Pros

  • Disguised as a rock
  • 300W Output
  • Longer than standard cord
  • Works well in low temperatures

Cons

  • Not suitable for some pond sizes
  • Some longevity issues reported

5. Apollo 11 Digital Spa Controller/Spa Pack – Best Inline Electrical Heater for Ponds

Designed for small spas, this electric heater has the potential to become a great basis for your pond’s heating system. Unlike de-icers and submersibles, however, you’ll have to install it into a complete system and wire it up.

The linked model is a 5.5KW pump, suitable for ponds of up to 5000 gallons in moderate climates or 1500 gallons in more inclement weather. This particular set includes most of what you need to wire into your pond, including the thermostat.

The “digital spa controller” is a nice little piece of hardware, with an attractive and easy-to-use display. It’s also available in both a 120V and 240V configuration, so you don’t need to pay for a new outlet if you don’t have high voltage access in your home.

That said, this isn’t a “plug-and-play” solution like de-icers or submersibles. Most of the stuff you’ll need is here, but make sure that you plan carefully for any extras you may need if you install it yourself.

If you’re up to the task or have an installer up to it, the Apollo 11 Digital Spa Controller offers a lot of utility and reliability. It’s just a matter of getting the system installed and running in the first place.

Pros

  • Very reliable
  • Awesome thermostat control
  • Comes with most of what you need
  • Much more reliable than a de-icer

Cons

  • Expensive
  • Installation is a major task

6. FibroPool FH120 – Best Inline Heat Pump for Large Ponds

Among the most reliable heat pumps in the business, FibroPool makes some excellent heaters. This is on the smaller side of their range, featuring roughly 20,000 BTUs. It functions off of a standard 120V outlet as well, making it perfect for a home pond.

It’s rated for pools of up to 7500 gallons, so it will work well for large ponds in the 1500-5000 gallon range. Everything about this heat pump is high-quality, and it’s designed for serious longevity.

The pump is relatively easy to install if you’ve ever done work on your pumps and filters before. The instructions are easy to follow, just be aware you may end up making a trip or three to the hardware store to get the fittings you need.

This is a high-end heat pump and the cost matches up. It also faces the same complexity problem of all of the better systems. They’re just harder to use than de-icers or submersible heaters.

If you’re willing to pay a premium, however, then the FibroPool FH120 is an excellent option for larger ponds.

Pros

  • Works well for ponds in the 1500-5000 gallon range in winter
  • High-quality construction
  • Highly efficient
  • Easier to install than most electric systems

Cons

  • Premium product at a premium price
  • More involved installation than simpler systems

Why a Pond Heater/De-Icer?

In chilly climates, a heater can help keep your fish healthy throughout the year. In places where the temperature drops below 32°F (0°C), you also have to worry about the pond’s surface freezing over.

If the surface of a pond freezes over, you lose all of the gas exchange that occurs at the surface of the water. That prevents oxygen from getting into the water, even if the fish are tolerant of the low temperatures beneath the surface of the ice.

A pond de-icer should be used in any pond where the temperature hits under freezing. Actual heater use may vary, and it depends a lot on whether or not you’re willing to pay the bills that come with them.

In smaller ponds, under 100 gallons, for example,  it may be a better idea to just bring your fish indoors for the winter. If you’ve got room, Koi and Goldfish are easy to keep with standard aquarium equipment.

You may not want to heat your pond year-round if you only have temperate fish in the pond, you’ll have to do the math in your area but the usual rule of thumb is 1W per 1 gallon (roughly 4L).

While pond heaters aren’t a requirement for all ponds, they’re something to look into. If ice is a risk then you need to make sure you have at least a spot heater to keep your fish healthy throughout the winter months.

Pond Heater and De-Icer Buyer’s Guide

Buying these devices can be a bit of a chore, there’s a lot to learn after all.

Upfront, the biggest questions you need an answer for are the following:

  • Does your pond ice over?
  • What’s the volume of the pond?
  • How deep does the pond get?
  • Is there any life other than fish in the pond?
  • How much are you willing to spend?

Once you have those answers, you’ll find it easy to use the rest of this guide to guide you to making the right purchase.

Types of Pond Heaters/De-Icers

There are four main types of pond heaters that you’ll find available.

  1. Pond De-Icers
  2. Submersible Heaters
  3. Gas-fired Boilers
  4. Inline Heat Pumps

All four have their own sets of advantages and disadvantages, but it’s the first choice you have to make when you’re trying to find the right fit for your pond.

I’ve excluded solar-powered heaters for this article since they’re often not enough to keep a whole pond heated. If you just need a few degrees and don’t mind a bit of temperature fluctuation I recommend taking a look at this one from SunQuest.

De-Icers

Pond de-icers are the most commonly used. These units are small, relatively cheap, and don’t require a ton of power to run. They float at the surface, and most require a minimum depth of 18” (45cm). 

The way they work is simple: they have a heating element that you plug in and a thermostat that shuts the heater down at the right temperature. This creates a small “hot spot” in the ice of your pond, which keeps ice off the surface in a small radius.

The problem is that it only leaves a small hole for gas exchange in most cases.

Because of that, de-icers are often paired with a pond aerator during the winter months, creating both a break in the ice and increasing the oxygen dissolved in the water.

Pros

  • Cheapest option
  • Doesn’t require a lot of power
  • Minimal maintenance

Cons

  • Doesn’t heat the whole pond
  • Tend to have longevity and reliability issues

Takeaway: Best for those who don’t mind if the pond is frozen and just want to make sure their fish are healthy in the cold months. These are a suitable option for all ponds with just koi or goldfish. Pair with aeration for the best results.

Submersible

Submersible heaters use an electric heating element to heat water like a standard aquarium heater. This has the effect of heating the whole pond, at least when you have sufficient wattage.

The problem for most is that submersible heaters are expensive to run. At 1W per gallon, a large pond can be a huge addition to your power bill. They’re generally limited to smaller ponds, 500 gallons is about where they top out in their usefulness.

While these heaters take a lot of power, they’re usually very reliable and have a lower upfront cost than other whole pond heaters.

On the other hand, if you just want to keep your pond toasty and a higher electric bill isn’t a major issue these might be for you.

Pros

  • Low upfront cost
  • Low maintenance
  • Great for small ponds

Cons

  • Limited in overall capacity
  • Expensive to run

Takeaway: For small ponds, a submersible is a great solution. You just need to make sure that you’re aware of the power requirements and limitations of this style of heater.

Gas-fired Pond Heaters

Using natural gas to heat the water is a win for your utility bills, but it will take a lot of time to make your money back. Most of these systems are designed for pools, so they’re reserved for the big boys.

It’s a natural fit, it would seem. They operate by passing water over a heat exchanger then passing it back into the pond, creating a stable temperature.

The problems arise when you start to look at two things: cost and installation. 

These heaters have a high upfront cost, with only solar heaters being comparable, and the drain on your wallet doesn’t end there. You also have to pay a professional for installation since it’s a gas appliance and work out the logistics of the piping.

While it’s a huge chore, it’s also much cheaper than using an electric system in the long run. You’ll most likely need a professional to help you pick out the other components in the system, these aren’t a “one-and-done” sort of deal.

If you’re looking into using a gas boiler then you should contact a local pond or pool company, they’ll have access to higher-grade equipment and know what you need to make the system work.

Pros

  • Lower monthly costs than electric models
  • Reliable even in inclement weather
  • Suitable for very large ponds

Cons

  • High upfront cost
  • Requires professional installation

Takeaway: The best option for large ponds, with a lower monthly cost than electric equivalents. The obstacle is the high upfront costs and continuing maintenance of the system.

Inline Heater

Inline heaters function in the same way as gas boilers but they’re cheaper upfront and simpler to build a system for. These systems are also usually adapted from pool equipment.

Inline heaters require a lot of electricity, but they’re the best option for keeping the whole pond heated without spending too much on the front end. The monthly costs will add up, but it still takes a gas system a few years to break even.

Most of those in use are adapted from hot tub or spa heaters. You may have to add a thermostat if the heater doesn’t have a low enough setting. Hot tubs tend to run at a high temperature.

Still, these are the best option for those trying to keep a heated pond. I’ve primarily seen them used for ponds housing tropical fish, rather than to keep ice off the pond in the winter.

Pros

  • Simpler to use than gas systems
  • Low upfront costs
  • Suitable for heating larger ponds

Cons

  • High running costs
  • Requires some research since most parts are designed for hot tubs

Reliability

Pond heaters and de-icers need to remain reliable throughout the cold season, or you risk your fish’s health. It’s a top priority.

Fortunately, the majority of pond heaters do the trick year-round. De-icers may bear a closer look if you’re going for an off-brand product, and submersibles need to be checked regularly.

You may want a backup if you go with a de-icer. The reliability issues of sticking a heating element in a bubble and throwing it in a pond can cost you your fish if the heater fails.

Systems using gas or electric inline heating tend to be the most reliable, but the latter will quit functioning if your power runs out. 

Plan accordingly.

Wattage or BTU Output

For the most part, electrical heaters will be provided with a wattage measurement while gas boilers come with a BTU output rating. BTUs, or British Thermal Units, are just another measure of heat.

1 Watt per Gallon is a good guideline for heating a whole pond with electricity. You may need to go a bit higher if you’re really far North but in most places, that’s all you need to shoot for.

For BTUs you should be looking at around 6 per gallon or higher. Going higher than that is fine, but any gas installation should have a professional involved and I’d recommend deferring to their expertise when picking out a pump.

Thermostat Controls

Thermostat controls allow you to set the temperature of your pond’s heater. A lot of de-icers may not come with an internal thermostat, instead, they’ll be set to a moderate temperature just to keep the ice out of the water.

If you’re heating the whole pond, then you should look for something with a thermostat so that you can control the temperature tightly. Pool and spa equipment tend to have the best thermostatic controls, while many de-icers lack them.

Power Input

Many inline heaters require a 240V outlet. Keep that in mind when you’re looking for one, as there are few things more disappointing than realizing you now have to pay an electrician to handle your expensive purchase.

Installing a 240V outlet is an option, but you’re looking at a few hundred dollars at the very least.

Keep Your Koi Warm This Winter

Finding the best pond heater and de-icer for your pond can be a chore, but it’s a necessary part of making sure your fish and plants are healthy. Spend some time figuring out what you need, there’s something perfectly suited for your pond out there.

So, get to it! Your fish are about to have a much nicer winter.