Keep That Pond De-Iced This Winter!

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The weather is continuing to cool and the leaves have stopped falling into your pond. It looks like winter is around the corner once again! If you live in a region where your pond tends to freeze over you may find yourself outdoors daily (often repeatedly) cracking a hole open in the ice for gas exchange. 

But what if there was a tool that did that for you? Any one of the best pond de-icers on the market are capable of keeping a hole open, allowing you to stay warm and secure in the knowledge that your fish are thriving outdoors!

The Best Pond De-Icers of 2021

There are dozens, if not hundreds of pond de-icers on the market right now! But I’ve taken the time to curate that list down to the top four models that meet the needs of the majority of pond keepers! They are:

• Tetra Pond De Icer
• Laguna PowerHeat Pond De-Icer
• Aquascape 39000 Pond Heater and De-icer **Top Choice**
• DANNER MANUFACTURING 2175 Pondmaster Pond De-Icer

Pond de-icers aren’t always on the radar of even savvy pond keepers. Have you considered why a pond de-icer is important in the first place?

The Benefits of Using a Pond De-Icer

If this is your first pond overwintering season then you may not be aware of why you need a de-icer in the first place. A pond de-icer is used to keep a hole open in the ice that forms over the top of your pond like a cap.

Holes in the ice allow gas exchange to continue unimpeded. If you’re keeping goldfish, koi, and other outdoor pond fish that can go into winter hibernation their oxygen needs and carbon dioxide releases slow down greatly but not entirely. A well stocked pond that’s frozen over entirely can cause fish to suffocate if there isn’t a hole for proper gas exchange.

Decomposition of organic waste matter also slows down greatly but doesn’t stop entirely. If oxygen levels fall below a certain point anaerobic (without oxygen) processes start to dominate, which produces extremely poisonous byproducts that fish shouldn’t be exposed to. So as simple as a hole in the ice sounds, it’s a life or death matter for pond fish overwintering outdoors!

My Top Choices for the Best Pond De-Icers

TetraPond De-Icer

Tetra has been a staple of aquarists around the world for decades. From food to filters they make name brand products that meet each need of modern fish keepers and their TetraPond De-Icer is no different! 

Unlike the other models I’ve covered, the TetraPod design uses a thermoplastic shell molded in the shape of a rock! This allows it to seamlessly blend into the outdoor aesthetic of any pond. A few color options such as black or red would have been nice but not entirely necessary.

This unit is rated as safe to operate down to -28.8°C (-20 Fahrenheit) and includes a 15 foot cord for reaching nearly any area of your freezing pond. 300 Watts of energy use make this an ideal model for most regions where the ice stays under an inch in thickness. And the 3-year warranty ensures that you’ll be satisfied even if an issue should arise in the future!

Overall, this is a well balanced pond de-icer with few drawbacks. A longer cord would definitely have been helpful for ensuring the unit can reach from outlet to anywhere within your pond without needing an extension cord. And the plastic build isn’t as rugged as the stainless steel used by the Laguna and Aquascape designs. But it’s an attractive option that’s even more affordable than the DANNER Pondmaster!

Laguna PowerHeat Pond De-Icer

While it doesn’t blend in the way the TetraPond model does, you do have a much more durable and entirely corrosion-resistant stainless steel shell surrounding the heating element. A major issue with pond de-icers is that many times you aren’t aware that they’ve stopped running until the hole freezes solid. That’s why I like how you can tell when the Laguna is running thanks to the red pilot light. 

And if you live in an area where the winters are particularly harsh you can choose a 500W model instead of the standard 375W design for extra protection for your fish. A more powerful heater also keeps a larger hole open than a smaller one; critical if you have a high population density. More fish need more oxygen and release more carbon dioxide!

Unfortunately, I did find that many users report their Laguna PowerHeat De-Icers as weak or non-functional by the second or third year. It seems as if these models have quality control issues – the majority work as expected but you may end up having to replace yours sooner than expected. TetraPond’s 3 year warranty is much more confidence inspiring than the 1 year warranty Laguna offers.

Aquascape 39000 Pond Heater and De-icer

The Aquascape 39000 Pond Heater and De-icer is a great solution for pond keepers looking for a rugged, durable de-icer backed by a solid warranty! Thanks to the stainless steel construction you won’t have to deal with corrosion like rust forming on the unit. And the 300W output is sufficient for all but the coldest of winter nights.

Like the Laguna PowerHeat the Aquascape also has a red LED pilot light, letting you know with a glance that the unit is working properly. Just be aware that this unit isn’t regulated by a thermostat, meaning it will run regardless of the water and air temperature. You’ll want to place the Aquascape into your pond once you know ice is beginning to form.

Many users report that over the course of a few months the Aquascape Pond Heater may cause the GFCI outlet to trip. Resetting it is a simple button press but it can be worrisome having to do so regularly. The LED light helps in this regard as well! 

Occasionally units may only last a single season as well; Aquascape’s quality control isn’t as good as some of the other brands on the market. Thankfully, they honor any issues through a 3 year warranty with each purchase!

DANNER 2175 Pondmaster Pond De-Icer

Not only is the DANNER Pondmaster extremely affordable; it’s also one of the more reliable pond de-icers on the market. Considering the DANNER Pondmaster uses around 120W of power this is a unit you’ll want to use for small ponds in areas where the winters are fairly mild. 

You may still need to break open a hole on especially cold days. But the low power use also makes tripping a breaker much less likely. You also get a regulating thermostat, which ensures the unit only runs when the water temperature is cold enough for ice. Taken together, these features make the DANNER a highly efficient option for folks who don’t want to see their winter energy bill skyrocket!

Given how affordable and reliable this unit is, the downsides are minor. The red plastic construction isn’t as rugged as the stainless steel used by the Aquascape and Laguna models. And the bright cherry red tone tends to stick out like a sore thumb when viewing your pond. Lastly, I really would have liked an LED indicator light so I know that the unit is running without having to guess.

Which is the Overall Best Pond De-Icer?

Each of these pond de-icers has something to offer the discriminating pond keeper. But my favorite is the Aquascape 39000 Pond Heater and De-icer. This unit includes the most features of any pond de-icer.

The LED indicator light lets me know at a glance that all is operational. The stainless steel construction isn’t as attractive as the molded plastic of the TetraPond but it’s much more durable. Any build quality issues that arise in the first year will be backed by their 1 year warranty.

And I even have the option of upgrading from 375W to 500W if my pond’s size and the weather demands it. Just make sure that you have enough power not to trip the breaker when running this unit.

De-Icers and Pond Winterization

Shopping For a Pond De-Icer

Buying a pond de-icer based solely on the watts of energy output can be a little complicated. Because the temperatures as well as the volume of your pond affect how powerful of a de-icer you’ll need. A larger volume of icy water will more rapidly pull heat away from the de-icer working area, while a smaller pond may actually warm a couple of degrees, making things easier for the de-icer. 

Low power pond de-icers in mild to moderate climates are an ideal solution. They don’t cause your winter energy bill to go up nearly as much as high powered units. And the GFCI breaker is less likely to trip when the de-icer’s thermostat turns the unit on.

Another feature to consider is build quality! Pond de-icers are usually made from plastic or stainless steel, both of which have advantages and disadvantages. Plastic construction is more affordable – but on the other hand these units are more prone to scratching and cracks. Stainless steel models are a little pricier but in exchange you get a more durable unit likely to last you many years!

Preparing Your Pond for Winter

Prepping Your Pond Plants

Depending on your climate, you’ll want to stop fertilizing your plants somewhere between August and September in most temperate countries. If you’re keeping the  highly popular tropical water lilies then you’ll want to cut the stems and leaves back and remove the bulbs 60 to 90 days after you stop fertilizing. 

The bulbs can either be left as-is, or if you want to be extra careful, treat them with a fungicide. Lily bulbs will keep indoors at around 50-60℉ in a container with damp sand until spring returns! Other plants may need to be either cut back and left in place or removed entirely, depending on the species in question. 

Fall Pond Cleaning

I recommend clearing out your pond for fall one last time before winter’s approach. A pond vacuum is one of the best tools for reaching leaves, mulm, and other hard to get at debris that accumulates over the autumn. This matter will continue to decompose over the winter, which uses up oxygen that the fish need for survival. Having a pond de-icer ensures they won’t run out of oxygen but you can help provide even more of it by cleaning the pond before ice starts to form.

Shut Down All Exterior Flow Devices

Fountains, waterfall pumps, surface aerators, and other spray devices need to be shut down and removed to prevent ice from forming in the lines or pumps. We also don’t want spray to form an icy coating that can damage nearby equipment or make the area around your pond dangerous to walk on. Submerged circulation pumps with no exterior lines can remain, which actually help prevent ice from forming on the surface, much like a pond de-icer!

For a full detailed article check out this Koi Pond Winterization article.

Goldfish and Koi Hibernation

Fish Torpor

Hibernation is a common way to describe what happens to goldfish and koi once your pond ices over. But the actual term for the state that they enter is called torpor. Torpor is a little different from hibernation, which is a deeper, longer lasting process.

When fish go into torpor due to the cold they become extremely lethargic and their energy needs greatly diminish. They stop feeding entirely and move and breathe very little. But they are still conscious or sleeping lightly, unlike hibernating animals, which are in a state of deep sleep for weeks or months at a time.

Fall Feeding Habits

When caring for outdoor fish like goldfish and koi we don’t want to feed normally until winter, only to stop. That’s a recipe for intestinal bloat, which is often fatal. We need to carefully monitor the temperature and switch both our feed and our feeding schedule as fall and winter arrive.

If it’s already fall and temperatures are still warm then you can continue using a standard pellet that’s rich in nutrients and feed normally! But once the air temperature starts hitting 50-55℉ it’s time to switch to a fall pellet blend. 

Cold water foods use a higher proportion of wheat germ, which is much easier for your fish to digest as their metabolisms begin slowing. It’s processed faster and doesn’t sit in their systems for long. Going into torpor (hibernation) on a full stomach can be bad for your fish because food sitting in their insides can start to rot before it gets fully processed.

Make sure that you also carefully monitor your fish’s rhythms and eating habits. They will start to slow down as the water temperature drops, eating less and signaling to you that you can continue to cut back as the weather grows cold. And once winter has fully arrived, you can stop feeding entirely and get your pond de-icer in place for their hibernation period!

Conclusion

Overwintering a pond is simple and trouble-free once you take the right steps to ensure your fish’s survival. Vacuuming up loose debris, trimming back your plants, and offering cold water fish food are all important. But a pond de-icer ensures that plenty of oxygen is available during the long winter months where ice caps the water. And once spring comes around, you’re guaranteed to be greeted by happy, hungry faces once more!