The unique climate of Colorado, especially during winter, can pose challenges for maintaining the health and well-being of your prized koi fish. Ensure that your koi pond not only survives but thrives even in the heart of Colorado’s winter chill. Do you need a koi pond heater (deicer)?
Colorado's Climate and Your Pond:
Living on the Front Range, spanning from Parker up to Fort Collins, exposes your backyard oasis to diverse temperatures from December through February. The average temperature highs and lows hover between 49 and 19° Fahrenheit, occasionally reaching as high as 60°. However, short cold bursts can bring temperatures down to -5°, and in rare instances, even plummeting to -10 to -20°. These serious temperature drops are far less common. In Jan 2024 it did get down to -13° briefly.
How Winter Affects Pond Fish:
Understanding how koi and goldfish navigate winter in a Colorado pond is crucial. These resilient fish can overwinter successfully in ponds at least 3 feet deep (goldfish have been known to overwinter in as little as 18 inches!). Fish enter a hibernation-like state called “torpor.” Their metabolism slows to a crawl, allowing them to wait out the winter in the pond’s lowest point with very little movement. Come spring, their metabolisms revitalize with increasing water temperatures. When the water temperatures reach 50° again, they are hungry! Koi and goldfish still need oxygen and gas exchange which, brings us to the next point…about koi pond heaters…
The photo above shows the hole the aerator had made completely froze over from 2 days of brutally cold weather. This is exactly why a koi pond heater / deicer is needed!
The Role of De-Icers : a koi pond heater
It’s essential to clarify that a deicer doesn’t actively heat the water to cozy temperatures, but prevents the pond’s surface from freezing over completely. This is paramount for the survival of pond fish during winter. Fish require sufficient oxygen levels and gas exchange. When a pond freezes over entirely, harmful gases like ammonia can become trapped, posing a threat to the fish. As long as it doesn’t get super cold for days on end, an aerator can keep a hole open (see photo below). A deicer ensures that at least a small opening in the ice will remain even if it gets super cold, facilitating essential gas exchange.
Oxygen and Gas Exchange:
The importance of oxygen in a koi pond cannot be overstated. When a pond freezes completely, new oxygen struggles to enter, while harmful gases need an escape route. Fortunately, cold water will hold more dissolved oxygen than warm water so that only a small hole is necessary. But without proper gas exchange, the trapped gases, including ammonia, can poison the fish. (read - kill the fish!) An opening by the de-icer addresses this issue and ensures the pond's oxygen levels remain sufficient.
Consider your Specific Pond Environment:
A koi pond that is shaded by buildings or trees will freeze over much more quickly! An aerator won’t be enough for a pond in the shade and it may need 2 deicers, depending on the size of the pond. Installing a submersible, nonfloating heater where the stream/waterfall enters the pond can assist continuous water circulation even at -13°.
But do you need a koi pond heater?
YES! Even if your pond is in full sun and the aerator normally keeps it from fully freezing over, you don’t want to be stuck in a bad situation when it is brutally cold outside.
Choosing and Placing a Floating Deicer:
Deicers (pond heaters) come in a range of wattages, from 300 to 2000 watts. For most ponds, a 300-watt deicer is sufficient to keep a small hole open in the ice. It’s essential to choose a deicer that only activates when the water temperature reaches as low as 44° Fahrenheit, preventing unnecessary energy consumption. Many deicers also feature a safety mechanism that turns them off when removed from the water.
- Opt for a floating deicer.
- You won’t need to get out in the frigid wind to put in and take out the deicer in the middle of the winter. Simply place the deicer in the pond when outside temperatures can potentially reach freezing. Most deicers don’t remain on all the time, but only come on when the water temperature gets as cold as 44° Fahrenheit.
- Deicers range from 300 watts to 2000 watts. 300 watts is plenty to keep a small hole open in the ice and are more energy efficient.
- Look for a deicer that has a safety feature that turns it off when it is removed from the water.
- Place the deicer in a slightly shallow area of the pond that has good circulation so that gasses are easily pushed out and the device can easily be reached.
Enhancing Effectiveness with an Aerator:
For optimal results, consider using a deicer in conjunction with an aerator. The aerator promotes circulation and adds oxygen, ensuring that gases are easily pushed out. Proper placement in a slightly shallow area with good circulation is key to facilitating gas exchange and accessibility for maintenance. Remember that placing the aerator diffusor in the deepest part of the pond can disturb the natural heat distribution (thermo climb) as the warmest part of the water will be at the bottom of the pond. Bringing in the cold air to the warmest part of the water cools the whole system. Make sure to place the aerator diffusor in a shallow area.
Looking forward to having the pond cleaned? Read When to cleanout the pond
Don't Break the Ice:
After reading all this you may be tempted to break the ice on your waterfall or pond just to put the koi pond heater in. I can tell you from experience, this is a bad idea! Once we broke the ice just near where the waterfall entered our pond thinking it wouldn’t matter at all. It caused some of the ice to sink down, some of it to heave up and suddenly the waterfall was flowing ON TOP of the ice instead of into the pond! The more we tried to push ice around or break something, the worse the situation got.
Imagine if you were a fish and someone banged on the ice. That would be so loud it would feel like they were banging on your head! Remember than fish are in a hibernating state called, “torpor”. Introducing that kind of stress could really affect their health.
Believe it or not Pond Ice Protects the Fish!
Once the pond freezes mostly over, it shockingly protects the pond from frigid temperatures! It keeps out blowing leaves and protects from any would-be predators. At -13° most of our waterfall froze over. We could see and hear that the water was running underneath it. (yes, the photo below is our waterfall!) You can see that even the top of the biofall is frozen.
Below is a look at our pond at -13°. The aerator is keeping a small hole open. We have a floating heater near the skimmer as well. After 2 days of these temperatures, the waterfall was 100% frozen over the top! But we could barley see and hear the water running underneath!
Understanding the nuances of Colorado’s climate, the winter behavior of pond fish, and the role of de-icers is essential. Incorporate these insights into your pond care routine, and create a haven for your koi that withstands the challenges posed by Colorado’s winter. With the right knowledge and equipment, your koi pond in Colorado can thrive as it provides a cascade of water through beautiful ice formations bringing winter beauty in the midst of winter’s chill!
Thinking of spring? Read about a common spring pest in Keep Heron out of the Pond!
An Aquascape heater is shown here. The blue light means it is not currently on. When the light is red, it is actively heating. Doesn’t the ice look amazing here?
Do you need help with your pond? Call us at 720-523-1575
Kristi's Tips
If possible, it’s a good idea to plug the deicer (koi pond heater) into a different outlet than the pump is plugged into. That way, if for any reason that outlet fails to produce electricity, at least the pond will have the deicer!
When you know the weather is going to get supper cold, make sure the pond is full, but not overly full. You don’t want to have to add water during frigid temps and you don’t want the pond to overflow when everything melts.
If the skimmer window is adjustable, put it in the lowest placement so that as water becomes ice, the window is low enough for flowing water to continue to the skimmer!
Now this might be the most important tip on this list… DO NOT TURN OFF THE PUMP if it is pumping water! Seriously, some people freak out over the low temperature and unplug / turn off the pump. This is the quickest way to let the pond pipes freeze!